21201659684676 has 243 divisors, whose sum is σ = 57062175769053. Its totient is φ = 6892422878880.

The previous prime is 21201659684603. The next prime is 21201659684677. The reversal of 21201659684676 is 67648695610212.

The square root of 21201659684676 is 4604526.

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

21201659684676 is a `hidden beast` number, since 2 + 1 + 2 + 0 + 165 + 9 + 6 + 8 + 467 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 16834395644676 + 4367264040000 = 4102974^2 + 2089800^2 .

It is a tau number, because it is divible by the number of its divisors (243).

It is not an unprimeable number, because it can be changed into a prime (21201659684677) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 32075127786 + ... + 32075128446.

Almost surely, 2^{21201659684676} is an apocalyptic number.

21201659684676 is the 4604526-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21201659684676

21201659684676 is an abundant number, since it is smaller than the sum of its proper divisors (35860516084377).

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

21201659684676 is an frugal number, since it uses more digits than its factorization.

21201659684676 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1436 (or 709 counting only the distinct ones).

The product of its (nonzero) digits is 52254720, while the sum is 63.

The spelling of 21201659684676 in words is "twenty-one trillion, two hundred one billion, six hundred fifty-nine million, six hundred eighty-four thousand, six hundred seventy-six".