21457761431 has 2 divisors, whose sum is σ = 21457761432. Its totient is φ = 21457761430.

The previous prime is 21457761421. The next prime is 21457761449. The reversal of 21457761431 is 13416775412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21457761431 - 2²² = 21453567127 is a prime.

It is a super-2 number, since 2×21457761431² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21457761421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10728880715 + 10728880716.

It is an arithmetic number, because the mean of its divisors is an integer number (10728880716).

Almost surely, 2^21457761431 is an apocalyptic number.

21457761431 is a deficient number, since it is larger than the sum of its proper divisors (1).

21457761431 is an equidigital number, since it uses as much as digits as its factorization.

21457761431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 141120, while the sum is 41.

The spelling of 21457761431 in words is "twenty-one billion, four hundred fifty-seven million, seven hundred sixty-one thousand, four hundred thirty-one".