31857721644 has 48 divisors (see below), whose sum is σ = 85227158016. Its totient is φ = 9072931200.

The previous prime is 31857721633. The next prime is 31857721657. The reversal of 31857721644 is 44612775813.

It is a junction number, because it is equal to n+sod(n) for n = 31857721593 and 31857721602.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 583617 + ... + 635864.

It is an arithmetic number, because the mean of its divisors is an integer number (1775565792).

Almost surely, 2^31857721644 is an apocalyptic number.

It is an amenable number.

31857721644 is an abundant number, since it is smaller than the sum of its proper divisors (53369436372).

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

31857721644 is a wasteful number, since it uses less digits than its factorization.

31857721644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1219806 (or 1219804 counting only the distinct ones).

The product of its digits is 1128960, while the sum is 48.

The spelling of 31857721644 in words is "thirty-one billion, eight hundred fifty-seven million, seven hundred twenty-one thousand, six hundred forty-four".