216664365621 has 32 divisors (see below), whose sum is σ = 317076664320. Its totient is φ = 130508715200.

The previous prime is 216664365587. The next prime is 216664365623. The reversal of 216664365621 is 126563466612.

It is a cyclic number.

It is not a de Polignac number, because 216664365621 - 2²⁷ = 216530147893 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216664365623) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 26708356 + ... + 26716466.

It is an arithmetic number, because the mean of its divisors is an integer number (9908645760).

Almost surely, 2^216664365621 is an apocalyptic number.

It is an amenable number.

216664365621 is a deficient number, since it is larger than the sum of its proper divisors (100412298699).

216664365621 is a wasteful number, since it uses less digits than its factorization.

216664365621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12977.

The product of its digits is 1866240, while the sum is 48.

It can be divided in two parts, 216664 and 365621, that added together give a palindrome (582285).

The spelling of 216664365621 in words is "two hundred sixteen billion, six hundred sixty-four million, three hundred sixty-five thousand, six hundred twenty-one".