6665521656 has 16 divisors (see below), whose sum is σ = 16663804200. Its totient is φ = 2221840544.

The previous prime is 6665521609. The next prime is 6665521663. The reversal of 6665521656 is 6561255666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 138865011 + ... + 138865058.

Almost surely, 2^6665521656 is an apocalyptic number.

It is an amenable number.

6665521656 is an abundant number, since it is smaller than the sum of its proper divisors (9998282544).

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

6665521656 is a wasteful number, since it uses less digits than its factorization.

6665521656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277730078 (or 277730074 counting only the distinct ones).

The product of its digits is 1944000, while the sum is 48.

The square root of 6665521656 is about 81642.6460619694. The cubic root of 6665521656 is about 1881.9643019637.

The spelling of 6665521656 in words is "six billion, six hundred sixty-five million, five hundred twenty-one thousand, six hundred fifty-six".