21991883 has 2 divisors, whose sum is σ = 21991884. Its totient is φ = 21991882.

The previous prime is 21991847. The next prime is 21991891. The reversal of 21991883 is 38819912.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21991883 - 2¹² = 21987787 is a prime.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21991883.

It is not a weakly prime, because it can be changed into another prime (21991813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10995941 + 10995942.

It is an arithmetic number, because the mean of its divisors is an integer number (10995942).

Almost surely, 2^21991883 is an apocalyptic number.

21991883 is a deficient number, since it is larger than the sum of its proper divisors (1).

21991883 is an equidigital number, since it uses as much as digits as its factorization.

21991883 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 41.

The square root of 21991883 is about 4689.5504048896. The cubic root of 21991883 is about 280.1694679883.

The spelling of 21991883 in words is "twenty-one million, nine hundred ninety-one thousand, eight hundred eighty-three".