165972634621 has 2 divisors, whose sum is σ = 165972634622. Its totient is φ = 165972634620.

The previous prime is 165972634549. The next prime is 165972634649. The reversal of 165972634621 is 126436279561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 91361712121 + 74610922500 = 302261^2 + 273150^2 .

It is a cyclic number.

It is not a de Polignac number, because 165972634621 - 2²³ = 165964246013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165972634721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82986317310 + 82986317311.

It is an arithmetic number, because the mean of its divisors is an integer number (82986317311).

Almost surely, 2^165972634621 is an apocalyptic number.

It is an amenable number.

165972634621 is a deficient number, since it is larger than the sum of its proper divisors (1).

165972634621 is an equidigital number, since it uses as much as digits as its factorization.

165972634621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3265920, while the sum is 52.

The spelling of 165972634621 in words is "one hundred sixty-five billion, nine hundred seventy-two million, six hundred thirty-four thousand, six hundred twenty-one".