31664640 has 320 divisors, whose sum is σ = 125706240. Its totient is φ = 6635520.

The previous prime is 31664639. The next prime is 31664653. The reversal of 31664640 is 4646613.

It is a tau number, because it is divible by the number of its divisors (320).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 31664598 and 31664607.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1021425 + ... + 1021455.

It is an arithmetic number, because the mean of its divisors is an integer number (392832).

Almost surely, 2^31664640 is an apocalyptic number.

31664640 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31664640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (62853120).

31664640 is an abundant number, since it is smaller than the sum of its proper divisors (94041600).

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

31664640 is a wasteful number, since it uses less digits than its factorization.

31664640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83 (or 67 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 30.

The square root of 31664640 is about 5627.1342617713. The cubic root of 31664640 is about 316.3672491450.

The spelling of 31664640 in words is "thirty-one million, six hundred sixty-four thousand, six hundred forty".