646656647839020 has 960 divisors, whose sum is σ = 2634887974118400. Its totient is φ = 128924032112640.

The previous prime is 646656647839019. The next prime is 646656647839051. The reversal of 646656647839020 is 20938746656646.

646656647839020 is a `hidden beast` number, since 6 + 4 + 6 + 6 + 5 + 66 + 478 + 3 + 90 + 2 + 0 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 646656647839020.

It is an unprimeable number.

It is a polite number, since it can be written in 319 ways as a sum of consecutive naturals, for example, 1089284475 + ... + 1089877965.

It is an arithmetic number, because the mean of its divisors is an integer number (2744674973040).

Almost surely, 2^{646656647839020} is an apocalyptic number.

646656647839020 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 646656647839020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1317443987059200).

646656647839020 is an abundant number, since it is smaller than the sum of its proper divisors (1988231326279380).

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

646656647839020 is a wasteful number, since it uses less digits than its factorization.

646656647839020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 593940 (or 593929 counting only the distinct ones).

The product of its (nonzero) digits is 1881169920, while the sum is 72.

The spelling of 646656647839020 in words is "six hundred forty-six trillion, six hundred fifty-six billion, six hundred forty-seven million, eight hundred thirty-nine thousand, twenty".