165625510621561 has 2 divisors, whose sum is σ = 165625510621562. Its totient is φ = 165625510621560.

The previous prime is 165625510621427. The next prime is 165625510621633. The reversal of 165625510621561 is 165126015526561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 153851004661561 + 11774505960000 = 12403669^2 + 3431400^2 .

It is a cyclic number.

It is not a de Polignac number, because 165625510621561 - 2³¹ = 165623363137913 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 165625510621499 and 165625510621508.

It is not a weakly prime, because it can be changed into another prime (165625510628561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82812755310780 + 82812755310781.

It is an arithmetic number, because the mean of its divisors is an integer number (82812755310781).

Almost surely, 2^{165625510621561} is an apocalyptic number.

It is an amenable number.

165625510621561 is a deficient number, since it is larger than the sum of its proper divisors (1).

165625510621561 is an equidigital number, since it uses as much as digits as its factorization.

165625510621561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3240000, while the sum is 52.

The spelling of 165625510621561 in words is "one hundred sixty-five trillion, six hundred twenty-five billion, five hundred ten million, six hundred twenty-one thousand, five hundred sixty-one".