21621244 has 12 divisors (see below), whose sum is σ = 38551464. Its totient is φ = 10606544.

The previous prime is 21621239. The next prime is 21621277. The reversal of 21621244 is 44212612.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 50782 + ... + 51205.

It is an arithmetic number, because the mean of its divisors is an integer number (3212622).

Almost surely, 2^21621244 is an apocalyptic number.

It is an amenable number.

21621244 is a deficient number, since it is larger than the sum of its proper divisors (16930220).

21621244 is a wasteful number, since it uses less digits than its factorization.

21621244 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 102044 (or 102042 counting only the distinct ones).

The product of its digits is 768, while the sum is 22.

The square root of 21621244 is about 4649.8649442753. The cubic root of 21621244 is about 278.5866018722.

Adding to 21621244 its reverse (44212612), we get a palindrome (65833856).

The spelling of 21621244 in words is "twenty-one million, six hundred twenty-one thousand, two hundred forty-four".