21109312431 has 12 divisors (see below), whose sum is σ = 30667481208. Its totient is φ = 13991527824.

The previous prime is 21109312397. The next prime is 21109312451. The reversal of 21109312431 is 13421390112.

21109312431 is a `hidden beast` number, since 211 + 0 + 9 + 3 + 12 + 431 = 666.

It is a de Polignac number, because none of the positive numbers 2^k-21109312431 is a prime.

It is a super-2 number, since 2×21109312431² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21109312395 and 21109312404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21109312451) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6777285 + ... + 6780398.

It is an arithmetic number, because the mean of its divisors is an integer number (2555623434).

Almost surely, 2^21109312431 is an apocalyptic number.

21109312431 is a deficient number, since it is larger than the sum of its proper divisors (9558168777).

21109312431 is a wasteful number, since it uses less digits than its factorization.

21109312431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13557862 (or 13557859 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The spelling of 21109312431 in words is "twenty-one billion, one hundred nine million, three hundred twelve thousand, four hundred thirty-one".