21556056431 has 24 divisors (see below), whose sum is σ = 27050763600. Its totient is φ = 17025990912.

The previous prime is 21556056421. The next prime is 21556056437. The reversal of 21556056431 is 13465065512.

It is a de Polignac number, because none of the positive numbers 2^k-21556056431 is a prime.

It is a super-2 number, since 2×21556056431² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21556056437) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 345095 + ... + 402743.

It is an arithmetic number, because the mean of its divisors is an integer number (1127115150).

Almost surely, 2^21556056431 is an apocalyptic number.

21556056431 is a deficient number, since it is larger than the sum of its proper divisors (5494707169).

21556056431 is a wasteful number, since it uses less digits than its factorization.

21556056431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58263 (or 58256 counting only the distinct ones).

The product of its (nonzero) digits is 108000, while the sum is 38.

The spelling of 21556056431 in words is "twenty-one billion, five hundred fifty-six million, fifty-six thousand, four hundred thirty-one".