165565006021 has 2 divisors, whose sum is σ = 165565006022. Its totient is φ = 165565006020.

The previous prime is 165565005997. The next prime is 165565006027. The reversal of 165565006021 is 120600565561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 94963201921 + 70601804100 = 308161^2 + 265710^2 .

It is a cyclic number.

It is not a de Polignac number, because 165565006021 - 2¹⁵ = 165564973253 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165565006027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82782503010 + 82782503011.

It is an arithmetic number, because the mean of its divisors is an integer number (82782503011).

Almost surely, 2^165565006021 is an apocalyptic number.

It is an amenable number.

165565006021 is a deficient number, since it is larger than the sum of its proper divisors (1).

165565006021 is an equidigital number, since it uses as much as digits as its factorization.

165565006021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 54000, while the sum is 37.

The spelling of 165565006021 in words is "one hundred sixty-five billion, five hundred sixty-five million, six thousand, twenty-one".