172904621 has 2 divisors, whose sum is σ = 172904622. Its totient is φ = 172904620.

The previous prime is 172904609. The next prime is 172904623. The reversal of 172904621 is 126409271.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 134328100 + 38576521 = 11590^2 + 6211^2 .

It is a cyclic number.

It is not a de Polignac number, because 172904621 - 2²⁶ = 105795757 is a prime.

Together with 172904623, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (172904623) 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, 86452310 + 86452311.

It is an arithmetic number, because the mean of its divisors is an integer number (86452311).

Almost surely, 2^172904621 is an apocalyptic number.

It is an amenable number.

172904621 is a deficient number, since it is larger than the sum of its proper divisors (1).

172904621 is an equidigital number, since it uses as much as digits as its factorization.

172904621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 172904621 is about 13149.3201725412. The cubic root of 172904621 is about 557.1030465371.

The spelling of 172904621 in words is "one hundred seventy-two million, nine hundred four thousand, six hundred twenty-one".