31328640 has 384 divisors, whose sum is σ = 132559200. Its totient is φ = 6967296.

The previous prime is 31328629. The next prime is 31328651. The reversal of 31328640 is 4682313.

It is a happy number.

31328640 is a `hidden beast` number, since 3 + 13 + 2 + 8 + 640 = 666.

It is an interprime number because it is at equal distance from previous prime (31328629) and next prime (31328651).

It is a tau number, because it is divible by the number of its divisors (384).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 846702 + ... + 846738.

Almost surely, 2^31328640 is an apocalyptic number.

31328640 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 31328640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (66279600).

31328640 is an abundant number, since it is smaller than the sum of its proper divisors (101230560).

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

31328640 is a wasteful number, since it uses less digits than its factorization.

31328640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79 (or 54 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 31328640 is about 5597.1992996498. The cubic root of 31328640 is about 315.2442549971.

The spelling of 31328640 in words is "thirty-one million, three hundred twenty-eight thousand, six hundred forty".