31220461728 has 72 divisors (see below), whose sum is σ = 90238700916. Its totient is φ = 10236211200.

The previous prime is 31220461711. The next prime is 31220461729. The reversal of 31220461728 is 82716402213.

It is a happy number.

31220461728 is a `hidden beast` number, since 3 + 12 + 2 + 0 + 4 + 617 + 28 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 30355395984 + 865065744 = 174228^2 + 29412^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 31220461692 and 31220461701.

It is not an unprimeable number, because it can be changed into a prime (31220461729) 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, 870993 + ... + 906128.

Almost surely, 2^31220461728 is an apocalyptic number.

It is an amenable number.

31220461728 is an abundant number, since it is smaller than the sum of its proper divisors (59018239188).

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

31220461728 is a wasteful number, since it uses less digits than its factorization.

31220461728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1777198 (or 1777187 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 36.

The spelling of 31220461728 in words is "thirty-one billion, two hundred twenty million, four hundred sixty-one thousand, seven hundred twenty-eight".