646591871520 has 216 divisors, whose sum is σ = 2566739084364. Its totient is φ = 147792411648.

The previous prime is 646591871447. The next prime is 646591871521. The reversal of 646591871520 is 25178195646.

It is a happy number.

646591871520 is a `hidden beast` number, since 6 + 46 + 5 + 9 + 1 + 8 + 71 + 520 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 609879778704 + 36712092816 = 780948^2 + 191604^2 .

It is a super-2 number, since 2×646591871520² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (646591871521) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 4511299 + ... + 4652418.

Almost surely, 2^646591871520 is an apocalyptic number.

646591871520 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

646591871520 is an abundant number, since it is smaller than the sum of its proper divisors (1920147212844).

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

646591871520 is a wasteful number, since it uses less digits than its factorization.

646591871520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9163752 (or 9163734 counting only the distinct ones).

The product of its (nonzero) digits is 3628800, while the sum is 54.

The spelling of 646591871520 in words is "six hundred forty-six billion, five hundred ninety-one million, eight hundred seventy-one thousand, five hundred twenty".