21719756 has 12 divisors (see below), whose sum is σ = 38209920. Its totient is φ = 10802640.

The previous prime is 21719749. The next prime is 21719759. The reversal of 21719756 is 65791712.

It is a hoax number, since the sum of its digits (38) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21719759) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13451 + ... + 14978.

It is an arithmetic number, because the mean of its divisors is an integer number (3184160).

Almost surely, 2^21719756 is an apocalyptic number.

It is an amenable number.

21719756 is a deficient number, since it is larger than the sum of its proper divisors (16490164).

21719756 is a wasteful number, since it uses less digits than its factorization.

21719756 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28624 (or 28622 counting only the distinct ones).

The product of its digits is 26460, while the sum is 38.

The square root of 21719756 is about 4660.4459014133. The cubic root of 21719756 is about 279.0090651936.

The spelling of 21719756 in words is "twenty-one million, seven hundred nineteen thousand, seven hundred fifty-six".