165662621 has 2 divisors, whose sum is σ = 165662622. Its totient is φ = 165662620.

The previous prime is 165662599. The next prime is 165662663. The reversal of 165662621 is 126266561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 84842521 + 80820100 = 9211^2 + 8990^2 .

It is an emirp because it is prime and its reverse (126266561) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 165662621 - 2¹⁰ = 165661597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165662681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82831310 + 82831311.

It is an arithmetic number, because the mean of its divisors is an integer number (82831311).

Almost surely, 2^165662621 is an apocalyptic number.

It is an amenable number.

165662621 is a deficient number, since it is larger than the sum of its proper divisors (1).

165662621 is an equidigital number, since it uses as much as digits as its factorization.

165662621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 35.

The square root of 165662621 is about 12870.9992230596. Note that the first 3 decimals coincide. The cubic root of 165662621 is about 549.2138863113.

The spelling of 165662621 in words is "one hundred sixty-five million, six hundred sixty-two thousand, six hundred twenty-one".