666164483721 has 27 divisors (see below), whose sum is σ = 1057708873767. Its totient is φ = 403719726960.

The previous prime is 666164483713. The next prime is 666164483731. The reversal of 666164483721 is 127384461666.

The square root of 666164483721 is 816189.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 33242405625 + 632922078096 = 182325^2 + 795564^2 .

It is not a de Polignac number, because 666164483721 - 2³ = 666164483713 is a prime.

It is not an unprimeable number, because it can be changed into a prime (666164483731) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 26921871 + ... + 26946603.

Almost surely, 2^666164483721 is an apocalyptic number.

666164483721 is the 816189-th square number.

666164483721 is the 408095-th centered octagonal number.

It is an amenable number.

666164483721 is a deficient number, since it is larger than the sum of its proper divisors (391544390046).

666164483721 is an frugal number, since it uses more digits than its factorization.

666164483721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49494 (or 24747 counting only the distinct ones).

The product of its digits is 6967296, while the sum is 54.

The spelling of 666164483721 in words is "six hundred sixty-six billion, one hundred sixty-four million, four hundred eighty-three thousand, seven hundred twenty-one".