2311991 has 8 divisors (see below), whose sum is σ = 2548368. Its totient is φ = 2080000.

The previous prime is 2311957. The next prime is 2311993. The reversal of 2311991 is 1991132.

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 2311991 - 2¹⁸ = 2049847 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2311991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2311993) 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, 71 + ... + 2151.

It is an arithmetic number, because the mean of its divisors is an integer number (318546).

2^2311991 is an apocalyptic number.

2311991 is a deficient number, since it is larger than the sum of its proper divisors (236377).

2311991 is a wasteful number, since it uses less digits than its factorization.

2311991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2193.

The product of its digits is 486, while the sum is 26.

The square root of 2311991 is about 1520.5232651952. The cubic root of 2311991 is about 132.2296087905.

It can be divided in two parts, 231 and 1991, that added together give a palindrome (2222).

The spelling of 2311991 in words is "two million, three hundred eleven thousand, nine hundred ninety-one".