Discover a lot of information on the number 21: properties, mathematical operations, how to write it, symbolism, numerology, representations and many other interesting things!

In letters, the number 21 is written as: Twenty-one. And in other languages? how does it spell?

21 in other languages | |||
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Write 21 in english | Twenty-one | ||

Write 21 in french | Vingt et un | ||

Write 21 in spanish | Veintiuno | ||

Write 21 in portuguese | Vinte e um |

The number 21 is composed of:

1 iteration **of the number 2** : The number 2 (two) represents double, association, cooperation, union, complementarity. It is the symbol of duality.... Find out more about the number 2

1 iteration **of the number 1** : The number 1 (one) represents the uniqueness, the unique, a starting point, a beginning.... Find out more about the number 1

Other ways to write 21 | |||
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In letter | Twenty-one | ||

In roman numeral | XXI | ||

In binary | 10101 | ||

In octal | 25 | ||

In hexadecimal | 15 | ||

In US dollars | USD 21.00 ($) | ||

In euros | 21,00 EUR (€) |

Operations and solutions | |||
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21*2 | = | 42 | The double of 21 is 42 |

21*3 | = | 63 | The triple of 21 is 63 |

21/2 | = | 10.5 | The half of 21 is 10.500000 |

21/3 | = | 7 | The third of 21 is 7.000000 |

21^{2} |
= | 441 | The square of 21 is 441.000000 |

21^{3} |
= | 9261 | The cube of 21 is 9261.000000 |

√21 | = | 4.5825756949558 | The square root of 21 is 4.582576 |

log(21) | = | 3.0445224377234 | The natural (Neperian) logarithm of 21 is 3.044522 |

log10(21) | = | 1.3222192947339 | The decimal logarithm (base 10) of 21 is 1.322219 |

sin(21) | = | 0.83665563853606 | The sine of 21 is 0.836656 |

cos(21) | = | -0.54772926022427 | The cosine of 21 is -0.547729 |

tan(21) | = | -1.5274985276366 | The tangent of 21 is -1.527499 |