2115921 has 4 divisors (see below), whose sum is σ = 2821232. Its totient is φ = 1410612.

The previous prime is 2115877. The next prime is 2115923. The reversal of 2115921 is 1295112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 2115921 - 2¹⁰ = 2114897 is a prime.

It is a D-number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2115923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 352651 + ... + 352656.

It is an arithmetic number, because the mean of its divisors is an integer number (705308).

2^2115921 is an apocalyptic number.

It is an amenable number.

2115921 is a deficient number, since it is larger than the sum of its proper divisors (705311).

2115921 is an equidigital number, since it uses as much as digits as its factorization.

2115921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 705310.

The product of its digits is 180, while the sum is 21.

The square root of 2115921 is about 1454.6205690832. The cubic root of 2115921 is about 128.3807227395.

The spelling of 2115921 in words is "two million, one hundred fifteen thousand, nine hundred twenty-one".