21057634431 has 24 divisors (see below), whose sum is σ = 32261898240. Its totient is φ = 13198021200.

The previous prime is 21057634427. The next prime is 21057634439. The reversal of 21057634431 is 13443675012.

21057634431 is a `hidden beast` number, since 2 + 10 + 5 + 7 + 634 + 4 + 3 + 1 = 666.

It is not a de Polignac number, because 21057634431 - 2² = 21057634427 is a prime.

It is a super-2 number, since 2×21057634431² (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 (21057634439) 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, 447615 + ... + 492416.

It is an arithmetic number, because the mean of its divisors is an integer number (1344245760).

Almost surely, 2^21057634431 is an apocalyptic number.

21057634431 is a deficient number, since it is larger than the sum of its proper divisors (11204263809).

21057634431 is a wasteful number, since it uses less digits than its factorization.

21057634431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 940187 (or 940184 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 36.

The spelling of 21057634431 in words is "twenty-one billion, fifty-seven million, six hundred thirty-four thousand, four hundred thirty-one".