172405401565021 has 2 divisors, whose sum is σ = 172405401565022. Its totient is φ = 172405401565020.

The previous prime is 172405401564971. The next prime is 172405401565051. The reversal of 172405401565021 is 120565104504271.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 168238046776921 + 4167354788100 = 12970661^2 + 2041410^2 .

It is a cyclic number.

It is not a de Polignac number, because 172405401565021 - 2¹⁵ = 172405401532253 is a prime.

It is a super-2 number, since 2×172405401565021² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (172405401565051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86202700782510 + 86202700782511.

It is an arithmetic number, because the mean of its divisors is an integer number (86202700782511).

Almost surely, 2^{172405401565021} is an apocalyptic number.

It is an amenable number.

172405401565021 is a deficient number, since it is larger than the sum of its proper divisors (1).

172405401565021 is an equidigital number, since it uses as much as digits as its factorization.

172405401565021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 336000, while the sum is 43.

The spelling of 172405401565021 in words is "one hundred seventy-two trillion, four hundred five billion, four hundred one million, five hundred sixty-five thousand, twenty-one".