213181664656 has 15 divisors (see below), whose sum is σ = 413043053601. Its totient is φ = 106589908896.

The previous prime is 213181664617. The next prime is 213181664771. The reversal of 213181664656 is 656466181312.

The square root of 213181664656 is 461716.

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., 44556455056 + 168625209600 = 211084^2 + 410640^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 1789150 + ... + 1904578.

Almost surely, 2^213181664656 is an apocalyptic number.

213181664656 is the 461716-th square number.

It is an amenable number.

213181664656 is a deficient number, since it is larger than the sum of its proper divisors (199861388945).

213181664656 is an frugal number, since it uses more digits than its factorization.

213181664656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230866 (or 115431 counting only the distinct ones).

The product of its digits is 1244160, while the sum is 49.

Multiplying 213181664656 by its sum of digits (49), we get a square (10445901568144 = 3232012²).

The spelling of 213181664656 in words is "two hundred thirteen billion, one hundred eighty-one million, six hundred sixty-four thousand, six hundred fifty-six".