21399992 has 16 divisors (see below), whose sum is σ = 40349400. Its totient is φ = 10640160.

The previous prime is 21399979. The next prime is 21400003. The reversal of 21399992 is 29999312.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 5942 + ... + 8837.

Almost surely, 2^21399992 is an apocalyptic number.

It is an amenable number.

21399992 is a deficient number, since it is larger than the sum of its proper divisors (18949408).

21399992 is a wasteful number, since it uses less digits than its factorization.

21399992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14966 (or 14962 counting only the distinct ones).

The product of its digits is 78732, while the sum is 44.

The square root of 21399992 is about 4626.0125378127. The cubic root of 21399992 is about 277.6330752585.

The spelling of 21399992 in words is "twenty-one million, three hundred ninety-nine thousand, nine hundred ninety-two".