21399268 has 24 divisors (see below), whose sum is σ = 41094144. Its totient is φ = 9669600.

The previous prime is 21399239. The next prime is 21399299. The reversal of 21399268 is 86299312.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21399268.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6621 + ... + 9307.

It is an arithmetic number, because the mean of its divisors is an integer number (1712256).

Almost surely, 2^21399268 is an apocalyptic number.

It is an amenable number.

21399268 is a deficient number, since it is larger than the sum of its proper divisors (19694876).

21399268 is a wasteful number, since it uses less digits than its factorization.

21399268 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2883 (or 2881 counting only the distinct ones).

The product of its digits is 46656, while the sum is 40.

The square root of 21399268 is about 4625.9342840123. The cubic root of 21399268 is about 277.6299442821.

The spelling of 21399268 in words is "twenty-one million, three hundred ninety-nine thousand, two hundred sixty-eight".