21821768 has 16 divisors (see below), whose sum is σ = 42236160. Its totient is φ = 10558800.

The previous prime is 21821759. The next prime is 21821797. The reversal of 21821768 is 86712812.

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, 43748 + ... + 44243.

It is an arithmetic number, because the mean of its divisors is an integer number (2639760).

Almost surely, 2^21821768 is an apocalyptic number.

It is an amenable number.

21821768 is a deficient number, since it is larger than the sum of its proper divisors (20414392).

21821768 is a wasteful number, since it uses less digits than its factorization.

21821768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88028 (or 88024 counting only the distinct ones).

The product of its digits is 10752, while the sum is 35.

The square root of 21821768 is about 4671.3775270256. The cubic root of 21821768 is about 279.4451939224.

The spelling of 21821768 in words is "twenty-one million, eight hundred twenty-one thousand, seven hundred sixty-eight".