31984640 has 44 divisors (see below), whose sum is σ = 76737936. Its totient is φ = 12791808.

The previous prime is 31984639. The next prime is 31984643. The reversal of 31984640 is 4648913.

It is a self number, because there is not a number n which added to its sum of digits gives 31984640.

It is not an unprimeable number, because it can be changed into a prime (31984643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1997 + ... + 8243.

It is an arithmetic number, because the mean of its divisors is an integer number (1744044).

Almost surely, 2^31984640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31984640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38368968).

31984640 is an abundant number, since it is smaller than the sum of its proper divisors (44753296).

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

31984640 is an equidigital number, since it uses as much as digits as its factorization.

31984640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6272 (or 6254 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 31984640 is about 5655.4964415160. The cubic root of 31984640 is about 317.4294054303.

The spelling of 31984640 in words is "thirty-one million, nine hundred eighty-four thousand, six hundred forty".