165338021 has 2 divisors, whose sum is σ = 165338022. Its totient is φ = 165338020.

The previous prime is 165338011. The next prime is 165338023. The reversal of 165338021 is 120833561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 159112996 + 6225025 = 12614^2 + 2495^2 .

It is a cyclic number.

It is not a de Polignac number, because 165338021 - 2¹⁸ = 165075877 is a prime.

It is a super-2 number, since 2×165338021² = 54673322376392882, which contains 22 as substring.

Together with 165338023, it forms a pair of twin primes.

It is a Chen prime.

It is a pancake number, because a pancake can be divided into 165338021 parts by 18184 straight cuts.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165338023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82669010 + 82669011.

It is an arithmetic number, because the mean of its divisors is an integer number (82669011).

Almost surely, 2^165338021 is an apocalyptic number.

It is an amenable number.

165338021 is a deficient number, since it is larger than the sum of its proper divisors (1).

165338021 is an equidigital number, since it uses as much as digits as its factorization.

165338021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 165338021 is about 12858.3832965113. The cubic root of 165338021 is about 548.8549411435.

The spelling of 165338021 in words is "one hundred sixty-five million, three hundred thirty-eight thousand, twenty-one".