172397881 has 2 divisors, whose sum is σ = 172397882. Its totient is φ = 172397880.

The previous prime is 172397861. The next prime is 172397891. The reversal of 172397881 is 188793271.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 167469481 + 4928400 = 12941^2 + 2220^2 .

It is an emirp because it is prime and its reverse (188793271) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 172397881 - 2¹⁹ = 171873593 is a prime.

It is a super-2 number, since 2×172397881² = 59442058746580322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (172397861) 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, 86198940 + 86198941.

It is an arithmetic number, because the mean of its divisors is an integer number (86198941).

Almost surely, 2^172397881 is an apocalyptic number.

It is an amenable number.

172397881 is a deficient number, since it is larger than the sum of its proper divisors (1).

172397881 is an equidigital number, since it uses as much as digits as its factorization.

172397881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 169344, while the sum is 46.

The square root of 172397881 is about 13130.0373571441. The cubic root of 172397881 is about 556.5582709728.

The spelling of 172397881 in words is "one hundred seventy-two million, three hundred ninety-seven thousand, eight hundred eighty-one".