21099968 has 14 divisors (see below), whose sum is σ = 41870376. Its totient is φ = 10549952.

The previous prime is 21099959. The next prime is 21099973. The reversal of 21099968 is 86999012.

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 as a sum of consecutive naturals, namely, 164780 + ... + 164907.

Almost surely, 2^21099968 is an apocalyptic number.

It is an amenable number.

21099968 is a deficient number, since it is larger than the sum of its proper divisors (20770408).

21099968 is an equidigital number, since it uses as much as digits as its factorization.

21099968 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329699 (or 329689 counting only the distinct ones).

The product of its (nonzero) digits is 69984, while the sum is 44.

The square root of 21099968 is about 4593.4701479383. The cubic root of 21099968 is about 276.3295091327.

The spelling of 21099968 in words is "twenty-one million, ninety-nine thousand, nine hundred sixty-eight".