31516784640 has 768 divisors, whose sum is σ = 125578252800. Its totient is φ = 7431782400.

The previous prime is 31516784627. The next prime is 31516784659. The reversal of 31516784640 is 4648761513.

31516784640 is a `hidden beast` number, since 3 + 1 + 516 + 78 + 4 + 64 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (768).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 130774920 + ... + 130775160.

It is an arithmetic number, because the mean of its divisors is an integer number (163513350).

Almost surely, 2^31516784640 is an apocalyptic number.

31516784640 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 31516784640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (62789126400).

31516784640 is an abundant number, since it is smaller than the sum of its proper divisors (94061468160).

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

31516784640 is a wasteful number, since it uses less digits than its factorization.

31516784640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 331 (or 305 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 45.

The spelling of 31516784640 in words is "thirty-one billion, five hundred sixteen million, seven hundred eighty-four thousand, six hundred forty".