21689828 has 24 divisors (see below), whose sum is σ = 39795840. Its totient is φ = 10324160.

The previous prime is 21689827. The next prime is 21689867. The reversal of 21689828 is 82898612.

It is not an unprimeable number, because it can be changed into a prime (21689821) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25433 + ... + 26271.

It is an arithmetic number, because the mean of its divisors is an integer number (1658160).

Almost surely, 2^21689828 is an apocalyptic number.

It is an amenable number.

21689828 is a deficient number, since it is larger than the sum of its proper divisors (18106012).

21689828 is a wasteful number, since it uses less digits than its factorization.

21689828 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1147 (or 1145 counting only the distinct ones).

The product of its digits is 110592, while the sum is 44.

The square root of 21689828 is about 4657.2339430181. The cubic root of 21689828 is about 278.8808559338.

The spelling of 21689828 in words is "twenty-one million, six hundred eighty-nine thousand, eight hundred twenty-eight".