165021121 has 2 divisors, whose sum is σ = 165021122. Its totient is φ = 165021120.

The previous prime is 165021097. The next prime is 165021127. The reversal of 165021121 is 121120561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 134096400 + 30924721 = 11580^2 + 5561^2 .

It is an emirp because it is prime and its reverse (121120561) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 165021121 - 2⁷ = 165020993 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (165021127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82510560 + 82510561.

It is an arithmetic number, because the mean of its divisors is an integer number (82510561).

Almost surely, 2^165021121 is an apocalyptic number.

It is an amenable number.

165021121 is a deficient number, since it is larger than the sum of its proper divisors (1).

165021121 is an equidigital number, since it uses as much as digits as its factorization.

165021121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 120, while the sum is 19.

The square root of 165021121 is about 12846.0546861673. The cubic root of 165021121 is about 548.5040571941.

Adding to 165021121 its reverse (121120561), we get a palindrome (286141682).

The spelling of 165021121 in words is "one hundred sixty-five million, twenty-one thousand, one hundred twenty-one".