2161921 has 8 divisors (see below), whose sum is σ = 2257920. Its totient is φ = 2067408.

The previous prime is 2161919. The next prime is 2161927. The reversal of 2161921 is 1291612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2161921 - 2¹ = 2161919 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2161892 and 2161901.

It is not an unprimeable number, because it can be changed into a prime (2161927) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3390 + ... + 3976.

It is an arithmetic number, because the mean of its divisors is an integer number (282240).

2^2161921 is an apocalyptic number.

It is an amenable number.

2161921 is a deficient number, since it is larger than the sum of its proper divisors (95999).

2161921 is a wasteful number, since it uses less digits than its factorization.

2161921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 743.

The product of its digits is 216, while the sum is 22.

The square root of 2161921 is about 1470.3472378999. The cubic root of 2161921 is about 129.3043910569.

The spelling of 2161921 in words is "two million, one hundred sixty-one thousand, nine hundred twenty-one".