165633521 has 2 divisors, whose sum is σ = 165633522. Its totient is φ = 165633520.

The previous prime is 165633509. The next prime is 165633541. The reversal of 165633521 is 125336561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 149793121 + 15840400 = 12239^2 + 3980^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165633521 is a prime.

It is not a weakly prime, because it can be changed into another prime (165633541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82816760 + 82816761.

It is an arithmetic number, because the mean of its divisors is an integer number (82816761).

Almost surely, 2^165633521 is an apocalyptic number.

It is an amenable number.

165633521 is a deficient number, since it is larger than the sum of its proper divisors (1).

165633521 is an equidigital number, since it uses as much as digits as its factorization.

165633521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16200, while the sum is 32.

The square root of 165633521 is about 12869.8687250492. The cubic root of 165633521 is about 549.1817264515.

The spelling of 165633521 in words is "one hundred sixty-five million, six hundred thirty-three thousand, five hundred twenty-one".