221525636656721 has 8 divisors (see below), whose sum is σ = 221562678700224. Its totient is φ = 221488597374480.

The previous prime is 221525636656699. The next prime is 221525636656771. The reversal of 221525636656721 is 127656636525122.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 221525636656721 - 2¹⁴ = 221525636640337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221525636656771) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 163006196 + ... + 164359578.

It is an arithmetic number, because the mean of its divisors is an integer number (27695334837528).

Almost surely, 2^{221525636656721} is an apocalyptic number.

It is an amenable number.

221525636656721 is a deficient number, since it is larger than the sum of its proper divisors (37042043503).

221525636656721 is a wasteful number, since it uses less digits than its factorization.

221525636656721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1380631.

The product of its digits is 54432000, while the sum is 59.

The spelling of 221525636656721 in words is "two hundred twenty-one trillion, five hundred twenty-five billion, six hundred thirty-six million, six hundred fifty-six thousand, seven hundred twenty-one".