172397521 has 2 divisors, whose sum is σ = 172397522. Its totient is φ = 172397520.

The previous prime is 172397503. The next prime is 172397531. The reversal of 172397521 is 125793271.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 167987521 + 4410000 = 12961^2 + 2100^2 .

It is a cyclic number.

It is not a de Polignac number, because 172397521 - 2¹⁷ = 172266449 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (172397501) 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, 86198760 + 86198761.

It is an arithmetic number, because the mean of its divisors is an integer number (86198761).

Almost surely, 2^172397521 is an apocalyptic number.

It is an amenable number.

172397521 is a deficient number, since it is larger than the sum of its proper divisors (1).

172397521 is an equidigital number, since it uses as much as digits as its factorization.

172397521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 26460, while the sum is 37.

The square root of 172397521 is about 13130.0236481127. The cubic root of 172397521 is about 556.5578835722.

The spelling of 172397521 in words is "one hundred seventy-two million, three hundred ninety-seven thousand, five hundred twenty-one".