666120400 has 60 divisors (see below), whose sum is σ = 1745852544. Its totient is φ = 242224000.

The previous prime is 666120391. The next prime is 666120407. The reversal of 666120400 is 4021666.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666120407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 71296 + ... + 80095.

Almost surely, 2^666120400 is an apocalyptic number.

It is an amenable number.

666120400 is an abundant number, since it is smaller than the sum of its proper divisors (1079732144).

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

666120400 is a wasteful number, since it uses less digits than its factorization.

666120400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151420 (or 151409 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 666120400 is about 25809.3083983279. The cubic root of 666120400 is about 873.3417955917.

The spelling of 666120400 in words is "six hundred sixty-six million, one hundred twenty thousand, four hundred".