31491720320 has 32 divisors (see below), whose sum is σ = 75284895420. Its totient is φ = 12596687872.

The previous prime is 31491720277. The next prime is 31491720331. The reversal of 31491720320 is 2302719413.

It can be written as a sum of positive squares in 2 ways, for example, as 30742712896 + 749007424 = 175336^2 + 27368^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24602267 + ... + 24603546.

Almost surely, 2^31491720320 is an apocalyptic number.

It is an amenable number.

31491720320 is an abundant number, since it is smaller than the sum of its proper divisors (43793175100).

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

31491720320 is an equidigital number, since it uses as much as digits as its factorization.

31491720320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49205832 (or 49205820 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 32.

The spelling of 31491720320 in words is "thirty-one billion, four hundred ninety-one million, seven hundred twenty thousand, three hundred twenty".