172505521 has 2 divisors, whose sum is σ = 172505522. Its totient is φ = 172505520.

The previous prime is 172505519. The next prime is 172505527. The reversal of 172505521 is 125505271.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 136072225 + 36433296 = 11665^2 + 6036^2 .

It is a cyclic number.

It is not a de Polignac number, because 172505521 - 2¹ = 172505519 is a prime.

Together with 172505519, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 172505521.

It is not a weakly prime, because it can be changed into another prime (172505527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86252760 + 86252761.

It is an arithmetic number, because the mean of its divisors is an integer number (86252761).

Almost surely, 2^172505521 is an apocalyptic number.

It is an amenable number.

172505521 is a deficient number, since it is larger than the sum of its proper divisors (1).

172505521 is an equidigital number, since it uses as much as digits as its factorization.

172505521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3500, while the sum is 28.

The square root of 172505521 is about 13134.1357157599. The cubic root of 172505521 is about 556.6740795663.

The spelling of 172505521 in words is "one hundred seventy-two million, five hundred five thousand, five hundred twenty-one".