21244939 has 4 divisors (see below), whose sum is σ = 22168656. Its totient is φ = 20321224.

The previous prime is 21244921. The next prime is 21244969. The reversal of 21244939 is 93944212.

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-21244939 is a prime.

It is a super-2 number, since 2×21244939² = 902694866227442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21244969) 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, 461824 + ... + 461869.

It is an arithmetic number, because the mean of its divisors is an integer number (5542164).

Almost surely, 2^21244939 is an apocalyptic number.

21244939 is a deficient number, since it is larger than the sum of its proper divisors (923717).

21244939 is an equidigital number, since it uses as much as digits as its factorization.

21244939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 923716.

The product of its digits is 15552, while the sum is 34.

The square root of 21244939 is about 4609.2232534344. The cubic root of 21244939 is about 276.9609219072.

The spelling of 21244939 in words is "twenty-one million, two hundred forty-four thousand, nine hundred thirty-nine".