165572021 has 2 divisors, whose sum is σ = 165572022. Its totient is φ = 165572020.

The previous prime is 165571927. The next prime is 165572081. The reversal of 165572021 is 120275561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 93508900 + 72063121 = 9670^2 + 8489^2 .

It is a cyclic number.

It is not a de Polignac number, because 165572021 - 2¹⁸ = 165309877 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165572081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82786010 + 82786011.

It is an arithmetic number, because the mean of its divisors is an integer number (82786011).

Almost surely, 2^165572021 is an apocalyptic number.

It is an amenable number.

165572021 is a deficient number, since it is larger than the sum of its proper divisors (1).

165572021 is an equidigital number, since it uses as much as digits as its factorization.

165572021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4200, while the sum is 29.

The square root of 165572021 is about 12867.4792014598. The cubic root of 165572021 is about 549.1137473431.

The spelling of 165572021 in words is "one hundred sixty-five million, five hundred seventy-two thousand, twenty-one".