21112331 has 4 divisors (see below), whose sum is σ = 21124200. Its totient is φ = 21100464.

The previous prime is 21112291. The next prime is 21112339. The reversal of 21112331 is 13321112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21112331 is a prime.

It is a super-2 number, since 2×21112331² = 891461040507122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21112339) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2666 + ... + 7023.

It is an arithmetic number, because the mean of its divisors is an integer number (5281050).

Almost surely, 2^21112331 is an apocalyptic number.

21112331 is a deficient number, since it is larger than the sum of its proper divisors (11869).

21112331 is an equidigital number, since it uses as much as digits as its factorization.

21112331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11868.

The product of its digits is 36, while the sum is 14.

The square root of 21112331 is about 4594.8156655082. The cubic root of 21112331 is about 276.3834680568.

Adding to 21112331 its reverse (13321112), we get a palindrome (34433443).

The spelling of 21112331 in words is "twenty-one million, one hundred twelve thousand, three hundred thirty-one".