646643974680 has 768 divisors, whose sum is σ = 2441650176000. Its totient is φ = 152035107840.

The previous prime is 646643974679. The next prime is 646643974699. The reversal of 646643974680 is 86479346646.

646643974680 is a `hidden beast` number, since 6 + 46 + 6 + 43 + 97 + 468 + 0 = 666.

It is a super-2 number, since 2×646643974680² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 780028506 + ... + 780029334.

It is an arithmetic number, because the mean of its divisors is an integer number (3179232000).

Almost surely, 2^646643974680 is an apocalyptic number.

646643974680 is a gapful number since it is divisible by the number (60) 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 646643974680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1220825088000).

646643974680 is an abundant number, since it is smaller than the sum of its proper divisors (1795006201320).

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

646643974680 is a wasteful number, since it uses less digits than its factorization.

646643974680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1045 (or 1024 counting only the distinct ones).

The product of its (nonzero) digits is 125411328, while the sum is 63.

The spelling of 646643974680 in words is "six hundred forty-six billion, six hundred forty-three million, nine hundred seventy-four thousand, six hundred eighty".