21788828 has 12 divisors (see below), whose sum is σ = 38590440. Its totient is φ = 10762992.

The previous prime is 21788827. The next prime is 21788857. The reversal of 21788828 is 82888712.

It is a super-2 number, since 2×21788828² = 949506051227168, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21788827) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32483 + ... + 33146.

It is an arithmetic number, because the mean of its divisors is an integer number (3215870).

Almost surely, 2^21788828 is an apocalyptic number.

It is an amenable number.

21788828 is a deficient number, since it is larger than the sum of its proper divisors (16801612).

21788828 is a wasteful number, since it uses less digits than its factorization.

21788828 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65716 (or 65714 counting only the distinct ones).

The product of its digits is 114688, while the sum is 44.

The square root of 21788828 is about 4667.8504688989. The cubic root of 21788828 is about 279.3045154312.

The spelling of 21788828 in words is "twenty-one million, seven hundred eighty-eight thousand, eight hundred twenty-eight".