172505687521 has 2 divisors, whose sum is σ = 172505687522. Its totient is φ = 172505687520.

The previous prime is 172505687503. The next prime is 172505687561. The reversal of 172505687521 is 125786505271.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 127476847521 + 45028840000 = 357039^2 + 212200^2 .

It is a cyclic number.

It is not a de Polignac number, because 172505687521 - 2²⁷ = 172371469793 is a prime.

It is not a weakly prime, because it can be changed into another prime (172505687561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86252843760 + 86252843761.

It is an arithmetic number, because the mean of its divisors is an integer number (86252843761).

Almost surely, 2^172505687521 is an apocalyptic number.

It is an amenable number.

172505687521 is a deficient number, since it is larger than the sum of its proper divisors (1).

172505687521 is an equidigital number, since it uses as much as digits as its factorization.

172505687521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1176000, while the sum is 49.

The spelling of 172505687521 in words is "one hundred seventy-two billion, five hundred five million, six hundred eighty-seven thousand, five hundred twenty-one".