172125521 has 2 divisors, whose sum is σ = 172125522. Its totient is φ = 172125520.

The previous prime is 172125511. The next prime is 172125523. The reversal of 172125521 is 125521271.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 168065296 + 4060225 = 12964^2 + 2015^2 .

It is an emirp because it is prime and its reverse (125521271) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 172125521 - 2²⁶ = 105016657 is a prime.

It is a Sophie Germain prime.

Together with 172125523, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (172125523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86062760 + 86062761.

It is an arithmetic number, because the mean of its divisors is an integer number (86062761).

Almost surely, 2^172125521 is an apocalyptic number.

It is an amenable number.

172125521 is a deficient number, since it is larger than the sum of its proper divisors (1).

172125521 is an equidigital number, since it uses as much as digits as its factorization.

172125521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1400, while the sum is 26.

The square root of 172125521 is about 13119.6616191120. The cubic root of 172125521 is about 556.2650266361.

Adding to 172125521 its reverse (125521271), we get a palindrome (297646792).

The spelling of 172125521 in words is "one hundred seventy-two million, one hundred twenty-five thousand, five hundred twenty-one".