666559656 has 96 divisors (see below), whose sum is σ = 2089401600. Its totient is φ = 188023680.

The previous prime is 666559633. The next prime is 666559657. The reversal of 666559656 is 656955666.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (666559657) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 31446 + ... + 48186.

It is an arithmetic number, because the mean of its divisors is an integer number (21764600).

Almost surely, 2^666559656 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 666559656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1044700800).

666559656 is an abundant number, since it is smaller than the sum of its proper divisors (1422841944).

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

666559656 is a wasteful number, since it uses less digits than its factorization.

666559656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16839 (or 16832 counting only the distinct ones).

The product of its digits is 8748000, while the sum is 54.

The square root of 666559656 is about 25817.8166389027. The cubic root of 666559656 is about 873.5337210212.

The spelling of 666559656 in words is "six hundred sixty-six million, five hundred fifty-nine thousand, six hundred fifty-six".