172256921 has 2 divisors, whose sum is σ = 172256922. Its totient is φ = 172256920.

The previous prime is 172256881. The next prime is 172256947. The reversal of 172256921 is 129652271.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 144841225 + 27415696 = 12035^2 + 5236^2 .

It is a cyclic number.

It is not a de Polignac number, because 172256921 - 2⁶ = 172256857 is a prime.

It is a super-3 number, since 3×172256921³ (a number of 26 digits) contains 333 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (172250921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86128460 + 86128461.

It is an arithmetic number, because the mean of its divisors is an integer number (86128461).

Almost surely, 2^172256921 is an apocalyptic number.

It is an amenable number.

172256921 is a deficient number, since it is larger than the sum of its proper divisors (1).

172256921 is an equidigital number, since it uses as much as digits as its factorization.

172256921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15120, while the sum is 35.

The square root of 172256921 is about 13124.6684148591. The cubic root of 172256921 is about 556.4065408680.

The spelling of 172256921 in words is "one hundred seventy-two million, two hundred fifty-six thousand, nine hundred twenty-one".