165402521 has 2 divisors, whose sum is σ = 165402522. Its totient is φ = 165402520.

The previous prime is 165402443. The next prime is 165402533. The reversal of 165402521 is 125204561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 116402521 + 49000000 = 10789^2 + 7000^2 .

It is a cyclic number.

It is not a de Polignac number, because 165402521 - 2¹⁰ = 165401497 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (165402121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82701260 + 82701261.

It is an arithmetic number, because the mean of its divisors is an integer number (82701261).

Almost surely, 2^165402521 is an apocalyptic number.

It is an amenable number.

165402521 is a deficient number, since it is larger than the sum of its proper divisors (1).

165402521 is an equidigital number, since it uses as much as digits as its factorization.

165402521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2400, while the sum is 26.

The square root of 165402521 is about 12860.8911433073. The cubic root of 165402521 is about 548.9263031146.

The spelling of 165402521 in words is "one hundred sixty-five million, four hundred two thousand, five hundred twenty-one".