21716828 has 12 divisors (see below), whose sum is σ = 43433712. Its totient is φ = 9307200.

The previous prime is 21716809. The next prime is 21716831. The reversal of 21716828 is 82861712.

21716828 is an admirable number.

It is a hoax number, since the sum of its digits (35) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

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, 387773 + ... + 387828.

It is an arithmetic number, because the mean of its divisors is an integer number (3619476).

Almost surely, 2^21716828 is an apocalyptic number.

21716828 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21716828 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21716828 is a wasteful number, since it uses less digits than its factorization.

21716828 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 775612 (or 775610 counting only the distinct ones).

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

The square root of 21716828 is about 4660.1317577940. The cubic root of 21716828 is about 278.9965270654.

The spelling of 21716828 in words is "twenty-one million, seven hundred sixteen thousand, eight hundred twenty-eight".