2166921 has 6 divisors (see below), whose sum is σ = 3130010. Its totient is φ = 1444608.

The previous prime is 2166919. The next prime is 2166937. The reversal of 2166921 is 1296612.

It can be written as a sum of positive squares in only one way, i.e., 2134521 + 32400 = 1461^2 + 180^2 .

It is not a de Polignac number, because 2166921 - 2¹ = 2166919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2166961) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 120376 + ... + 120393.

2^2166921 is an apocalyptic number.

It is an amenable number.

2166921 is a deficient number, since it is larger than the sum of its proper divisors (963089).

2166921 is a wasteful number, since it uses less digits than its factorization.

2166921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 240775 (or 240772 counting only the distinct ones).

The product of its digits is 1296, while the sum is 27.

The square root of 2166921 is about 1472.0465345905. The cubic root of 2166921 is about 129.4039975609.

The spelling of 2166921 in words is "two million, one hundred sixty-six thousand, nine hundred twenty-one".