2165921 has 2 divisors, whose sum is σ = 2165922. Its totient is φ = 2165920.

The previous prime is 2165903. The next prime is 2165929. The reversal of 2165921 is 1295612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1852321 + 313600 = 1361^2 + 560^2 .

It is a cyclic number.

It is not a de Polignac number, because 2165921 - 2⁶ = 2165857 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (2165929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1082960 + 1082961.

It is an arithmetic number, because the mean of its divisors is an integer number (1082961).

2^2165921 is an apocalyptic number.

It is an amenable number.

2165921 is a deficient number, since it is larger than the sum of its proper divisors (1).

2165921 is an equidigital number, since it uses as much as digits as its factorization.

2165921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1080, while the sum is 26.

The square root of 2165921 is about 1471.7068322190. The cubic root of 2165921 is about 129.3840885274.

The spelling of 2165921 in words is "two million, one hundred sixty-five thousand, nine hundred twenty-one".