666815520 has 144 divisors (see below), whose sum is σ = 2443488768. Its totient is φ = 152409600.

The previous prime is 666815519. The next prime is 666815543. The reversal of 666815520 is 25518666.

666815520 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9345 + ... + 37695.

It is an arithmetic number, because the mean of its divisors is an integer number (16968672).

Almost surely, 2^666815520 is an apocalyptic number.

666815520 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 666815520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1221744384).

666815520 is an abundant number, since it is smaller than the sum of its proper divisors (1776673248).

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

666815520 is a wasteful number, since it uses less digits than its factorization.

666815520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28383 (or 28368 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 39.

The square root of 666815520 is about 25822.7713462363. The cubic root of 666815520 is about 873.6454775799.

The spelling of 666815520 in words is "six hundred sixty-six million, eight hundred fifteen thousand, five hundred twenty".