165151621 has 2 divisors, whose sum is σ = 165151622. Its totient is φ = 165151620.

The previous prime is 165151619. The next prime is 165151627. The reversal of 165151621 is 126151561.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 119115396 + 46036225 = 10914^2 + 6785^2 .

It is a cyclic number.

It is not a de Polignac number, because 165151621 - 2¹ = 165151619 is a prime.

Together with 165151619, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 165151621.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165151627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82575810 + 82575811.

It is an arithmetic number, because the mean of its divisors is an integer number (82575811).

Almost surely, 2^165151621 is an apocalyptic number.

It is an amenable number.

165151621 is a deficient number, since it is larger than the sum of its proper divisors (1).

165151621 is an equidigital number, since it uses as much as digits as its factorization.

165151621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1800, while the sum is 28.

The square root of 165151621 is about 12851.1330628859. The cubic root of 165151621 is about 548.6486062043.

The spelling of 165151621 in words is "one hundred sixty-five million, one hundred fifty-one thousand, six hundred twenty-one".