2165021 has 4 divisors (see below), whose sum is σ = 2172252. Its totient is φ = 2157792.

The previous prime is 2165017. The next prime is 2165027. The reversal of 2165021 is 1205612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 511225 + 1653796 = 715^2 + 1286^2 .

It is a cyclic number.

It is not a de Polignac number, because 2165021 - 2² = 2165017 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2165027) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3146 + ... + 3771.

It is an arithmetic number, because the mean of its divisors is an integer number (543063).

2^2165021 is an apocalyptic number.

It is an amenable number.

2165021 is a deficient number, since it is larger than the sum of its proper divisors (7231).

2165021 is an equidigital number, since it uses as much as digits as its factorization.

2165021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7230.

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 2165021 is about 1471.4010330294. The cubic root of 2165021 is about 129.3661651571.

The spelling of 2165021 in words is "two million, one hundred sixty-five thousand, twenty-one".