2161021 has 4 divisors (see below), whose sum is σ = 2172412. Its totient is φ = 2149632.

The previous prime is 2161007. The next prime is 2161031. The reversal of 2161021 is 1201612.

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 509796 + 1651225 = 714^2 + 1285^2 .

It is a cyclic number.

It is not a de Polignac number, because 2161021 - 2¹⁵ = 2128253 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2160992 and 2161010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2161001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5406 + ... + 5791.

It is an arithmetic number, because the mean of its divisors is an integer number (543103).

2^2161021 is an apocalyptic number.

It is an amenable number.

2161021 is a deficient number, since it is larger than the sum of its proper divisors (11391).

2161021 is a wasteful number, since it uses less digits than its factorization.

2161021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11390.

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 2161021 is about 1470.0411558865. The cubic root of 2161021 is about 129.2864455808.

Adding to 2161021 its reverse (1201612), we get a palindrome (3362633).

The spelling of 2161021 in words is "two million, one hundred sixty-one thousand, twenty-one".