172220656721 has 16 divisors (see below), whose sum is σ = 176679379968. Its totient is φ = 167827334400.

The previous prime is 172220656711. The next prime is 172220656723. The reversal of 172220656721 is 127656022271.

It is a cyclic number.

It is not a de Polignac number, because 172220656721 - 2²⁶ = 172153547857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (172220656723) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2279081 + ... + 2353433.

It is an arithmetic number, because the mean of its divisors is an integer number (11042461248).

Almost surely, 2^172220656721 is an apocalyptic number.

It is an amenable number.

172220656721 is a deficient number, since it is larger than the sum of its proper divisors (4458723247).

172220656721 is a wasteful number, since it uses less digits than its factorization.

172220656721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74792.

The product of its (nonzero) digits is 141120, while the sum is 41.

Adding to 172220656721 its reverse (127656022271), we get a palindrome (299876678992).

The spelling of 172220656721 in words is "one hundred seventy-two billion, two hundred twenty million, six hundred fifty-six thousand, seven hundred twenty-one".