31657821938 has 6 divisors (see below), whose sum is σ = 47487110349. Its totient is φ = 15828785156.

The previous prime is 31657821893. The next prime is 31657821941. The reversal of 31657821938 is 83912875613.

It can be written as a sum of positive squares in 2 ways, for example, as 18964870369 + 12692951569 = 137713^2 + 112663^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=125813.

It is a super-2 number, since 2×31657821938² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 31657821938.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 188720 + ... + 314532.

Almost surely, 2^31657821938 is an apocalyptic number.

31657821938 is a deficient number, since it is larger than the sum of its proper divisors (15829288411).

31657821938 is an frugal number, since it uses more digits than its factorization.

31657821938 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 251628 (or 125815 counting only the distinct ones).

The product of its digits is 2177280, while the sum is 53.

The spelling of 31657821938 in words is "thirty-one billion, six hundred fifty-seven million, eight hundred twenty-one thousand, nine hundred thirty-eight".