666556100 has 144 divisors (see below), whose sum is σ = 1816550400. Its totient is φ = 206997120.

The previous prime is 666556091. The next prime is 666556139. The reversal of 666556100 is 1655666.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 304811 + ... + 306989.

Almost surely, 2^666556100 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 666556100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (908275200).

666556100 is an abundant number, since it is smaller than the sum of its proper divisors (1149994300).

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

666556100 is a wasteful number, since it uses less digits than its factorization.

666556100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2242 (or 2235 counting only the distinct ones).

The product of its (nonzero) digits is 32400, while the sum is 35.

The square root of 666556100 is about 25817.7477716396. The cubic root of 666556100 is about 873.5321676261.

The spelling of 666556100 in words is "six hundred sixty-six million, five hundred fifty-six thousand, one hundred".