2161931 has 4 divisors (see below), whose sum is σ = 2255952. Its totient is φ = 2067912.

The previous prime is 2161927. The next prime is 2161933. The reversal of 2161931 is 1391612.

It is a happy number.

2161931 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 2161931 - 2² = 2161927 is a prime.

It is a super-2 number, since 2×2161931² = 9347891297522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (23), and also a Moran number because the ratio is a prime number: 93997 = 2161931 / (2 + 1 + 6 + 1 + 9 + 3 + 1).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2161897 and 2161906.

It is not an unprimeable number, because it can be changed into a prime (2161933) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46976 + ... + 47021.

It is an arithmetic number, because the mean of its divisors is an integer number (563988).

2^2161931 is an apocalyptic number.

2161931 is a deficient number, since it is larger than the sum of its proper divisors (94021).

2161931 is an equidigital number, since it uses as much as digits as its factorization.

2161931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94020.

The product of its digits is 324, while the sum is 23.

The square root of 2161931 is about 1470.3506384533. The cubic root of 2161931 is about 129.3045904231.

The spelling of 2161931 in words is "two million, one hundred sixty-one thousand, nine hundred thirty-one".