664839718920 has 384 divisors, whose sum is σ = 2510320831200. Its totient is φ = 151119101952.

The previous prime is 664839718897. The next prime is 664839718931. The reversal of 664839718920 is 29817938466.

664839718920 is a `hidden beast` number, since 6 + 6 + 48 + 397 + 189 + 20 = 666.

It can be written as a sum of positive squares in 16 ways, for example, as 32805178884 + 632034540036 = 181122^2 + 795006^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 4137846 + ... + 4295514.

Almost surely, 2^664839718920 is an apocalyptic number.

664839718920 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 664839718920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1255160415600).

664839718920 is an abundant number, since it is smaller than the sum of its proper divisors (1845481112280).

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

664839718920 is a wasteful number, since it uses less digits than its factorization.

664839718920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157769 (or 157762 counting only the distinct ones).

The product of its (nonzero) digits is 31352832, while the sum is 63.

The spelling of 664839718920 in words is "six hundred sixty-four billion, eight hundred thirty-nine million, seven hundred eighteen thousand, nine hundred twenty".