21995983 has 4 divisors (see below), whose sum is σ = 22059720. Its totient is φ = 21932248.

The previous prime is 21995951. The next prime is 21995993. The reversal of 21995983 is 38959912.

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 21995983 - 2⁵ = 21995951 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21995903) 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, 31348 + ... + 32041.

It is an arithmetic number, because the mean of its divisors is an integer number (5514930).

Almost surely, 2^21995983 is an apocalyptic number.

21995983 is a deficient number, since it is larger than the sum of its proper divisors (63737).

21995983 is an equidigital number, since it uses as much as digits as its factorization.

21995983 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63736.

The product of its digits is 174960, while the sum is 46.

The square root of 21995983 is about 4689.9875266359. The cubic root of 21995983 is about 280.1868777972.

It can be divided in two parts, 21 and 995983, that added together give a square (996004 = 998²).

The spelling of 21995983 in words is "twenty-one million, nine hundred ninety-five thousand, nine hundred eighty-three".