2161621 has 16 divisors (see below), whose sum is σ = 2741760. Its totient is φ = 1655280.

The previous prime is 2161613. The next prime is 2161633. The reversal of 2161621 is 1261612.

It is not a de Polignac number, because 2161621 - 2³ = 2161613 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2161121) 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 15 ways as a sum of consecutive naturals, for example, 4950 + ... + 5368.

It is an arithmetic number, because the mean of its divisors is an integer number (171360).

2^2161621 is an apocalyptic number.

It is an amenable number.

2161621 is a deficient number, since it is larger than the sum of its proper divisors (580139).

2161621 is a wasteful number, since it uses less digits than its factorization.

2161621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 504.

The product of its digits is 144, while the sum is 19.

The square root of 2161621 is about 1470.2452176423. The cubic root of 2161621 is about 129.2984097850.

Subtracting from 2161621 its reverse (1261612), we obtain a palindrome (900009).

The spelling of 2161621 in words is "two million, one hundred sixty-one thousand, six hundred twenty-one".