31605402388 has 18 divisors (see below), whose sum is σ = 64339569546. Its totient is φ = 13545172368.

The previous prime is 31605402383. The next prime is 31605402397. The reversal of 31605402388 is 88320450613.

It can be written as a sum of positive squares in only one way, i.e., 22159895044 + 9445507344 = 148862^2 + 97188^2 .

It is a super-2 number, since 2×31605402388² (a number of 22 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 31605402388.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31605402383) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 80625831 + ... + 80626222.

Almost surely, 2^31605402388 is an apocalyptic number.

It is an amenable number.

31605402388 is an abundant number, since it is smaller than the sum of its proper divisors (32734167158).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31605402388 is a wasteful number, since it uses less digits than its factorization.

31605402388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161252071 (or 161252062 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 40.

The spelling of 31605402388 in words is "thirty-one billion, six hundred five million, four hundred two thousand, three hundred eighty-eight".