666405600 has 144 divisors (see below), whose sum is σ = 2479091328. Its totient is φ = 152317440.

The previous prime is 666405599. The next prime is 666405613. The reversal of 666405600 is 6504666.

It is a super-2 number, since 2×666405600² = 888192847422720000, which contains 22 as substring.

It is a congruent number.

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, 3034 + ... + 36633.

It is an arithmetic number, because the mean of its divisors is an integer number (17215912).

Almost surely, 2^666405600 is an apocalyptic number.

666405600 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 666405600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1239545664).

666405600 is an abundant number, since it is smaller than the sum of its proper divisors (1812685728).

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

666405600 is a wasteful number, since it uses less digits than its factorization.

666405600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39697 (or 39684 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 33.

The square root of 666405600 is about 25814.8329454211. The cubic root of 666405600 is about 873.4664184782.

The spelling of 666405600 in words is "six hundred sixty-six million, four hundred five thousand, six hundred".