21944731 has 4 divisors (see below), whose sum is σ = 21968712. Its totient is φ = 21920752.

The previous prime is 21944701. The next prime is 21944759. The reversal of 21944731 is 13744912.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21944731 is a prime.

It is a super-2 number, since 2×21944731² = 963142437324722, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21944693 and 21944702.

It is not an unprimeable number, because it can be changed into a prime (21944701) 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, 10561 + ... + 12466.

It is an arithmetic number, because the mean of its divisors is an integer number (5492178).

Almost surely, 2^21944731 is an apocalyptic number.

21944731 is a deficient number, since it is larger than the sum of its proper divisors (23981).

21944731 is an equidigital number, since it uses as much as digits as its factorization.

21944731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23980.

The product of its digits is 6048, while the sum is 31.

The square root of 21944731 is about 4684.5203596526. The cubic root of 21944731 is about 279.9690909759.

The spelling of 21944731 in words is "twenty-one million, nine hundred forty-four thousand, seven hundred thirty-one".