172372561 has 2 divisors, whose sum is σ = 172372562. Its totient is φ = 172372560.

The previous prime is 172372523. The next prime is 172372591. The reversal of 172372561 is 165273271.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 140280336 + 32092225 = 11844^2 + 5665^2 .

It is an emirp because it is prime and its reverse (165273271) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 172372561 - 2¹⁹ = 171848273 is a prime.

It is not a weakly prime, because it can be changed into another prime (172372591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86186280 + 86186281.

It is an arithmetic number, because the mean of its divisors is an integer number (86186281).

Almost surely, 2^172372561 is an apocalyptic number.

172372561 is the 5872-nd centered decagonal number.

It is an amenable number.

172372561 is a deficient number, since it is larger than the sum of its proper divisors (1).

172372561 is an equidigital number, since it uses as much as digits as its factorization.

172372561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17640, while the sum is 34.

The square root of 172372561 is about 13129.0731203692. The cubic root of 172372561 is about 556.5310224836.

The spelling of 172372561 in words is "one hundred seventy-two million, three hundred seventy-two thousand, five hundred sixty-one".