21399844 has 12 divisors (see below), whose sum is σ = 39078144. Its totient is φ = 10234664.

The previous prime is 21399839. The next prime is 21399901. The reversal of 21399844 is 44899312.

It is a junction number, because it is equal to n+sod(n) for n = 21399797 and 21399806.

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, 116212 + ... + 116395.

It is an arithmetic number, because the mean of its divisors is an integer number (3256512).

Almost surely, 2^21399844 is an apocalyptic number.

It is an amenable number.

21399844 is a deficient number, since it is larger than the sum of its proper divisors (17678300).

21399844 is a wasteful number, since it uses less digits than its factorization.

21399844 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232634 (or 232632 counting only the distinct ones).

The product of its digits is 62208, while the sum is 40.

The square root of 21399844 is about 4625.9965412871. The cubic root of 21399844 is about 277.6324352304.

The spelling of 21399844 in words is "twenty-one million, three hundred ninety-nine thousand, eight hundred forty-four".