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21255431 is a prime number
BaseRepresentation
bin101000100010…
…1010100000111
31110222212222012
41101011110013
520420133211
62035324435
7345445121
oct121052407
943885865
1021255431
1110aa857a
12715071b
1345329a2
142b74211
151cecd8b
hex1445507

21255431 has 2 divisors, whose sum is σ = 21255432. Its totient is φ = 21255430.

The previous prime is 21255419. The next prime is 21255439. The reversal of 21255431 is 13455212.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2k-21255431 is a prime.

It is a super-2 number, since 2×212554312 = 903586693991522, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21255397 and 21255406.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21255439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10627715 + 10627716.

It is an arithmetic number, because the mean of its divisors is an integer number (10627716).

Almost surely, 221255431 is an apocalyptic number.

21255431 is a deficient number, since it is larger than the sum of its proper divisors (1).

21255431 is an equidigital number, since it uses as much as digits as its factorization.

21255431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1200, while the sum is 23.

The square root of 21255431 is about 4610.3612656711. The cubic root of 21255431 is about 277.0065075995.

The spelling of 21255431 in words is "twenty-one million, two hundred fifty-five thousand, four hundred thirty-one".