21107928 has 32 divisors (see below), whose sum is σ = 55065600. Its totient is φ = 6729888.

The previous prime is 21107927. The next prime is 21107929. The reversal of 21107928 is 82970112.

It is an interprime number because it is at equal distance from previous prime (21107927) and next prime (21107929).

It is a junction number, because it is equal to n+sod(n) for n = 21107895 and 21107904.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21107921) 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, 18568 + ... + 19671.

It is an arithmetic number, because the mean of its divisors is an integer number (1720800).

Almost surely, 2^21107928 is an apocalyptic number.

It is an amenable number.

21107928 is an abundant number, since it is smaller than the sum of its proper divisors (33957672).

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

21107928 is a wasteful number, since it uses less digits than its factorization.

21107928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38271 (or 38267 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 30.

The square root of 21107928 is about 4594.3365135784. The cubic root of 21107928 is about 276.3642533615.

The spelling of 21107928 in words is "twenty-one million, one hundred seven thousand, nine hundred twenty-eight".