21642928 has 20 divisors (see below), whose sum is σ = 43067680. Its totient is φ = 10528704.

The previous prime is 21642923. The next prime is 21642937. The reversal of 21642928 is 82924612.

It is a junction number, because it is equal to n+sod(n) for n = 21642893 and 21642902.

It is not an unprimeable number, because it can be changed into a prime (21642923) 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, 17688 + ... + 18871.

It is an arithmetic number, because the mean of its divisors is an integer number (2153384).

Almost surely, 2^21642928 is an apocalyptic number.

It is an amenable number.

21642928 is a deficient number, since it is larger than the sum of its proper divisors (21424752).

21642928 is a wasteful number, since it uses less digits than its factorization.

21642928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36604 (or 36598 counting only the distinct ones).

The product of its digits is 13824, while the sum is 34.

The square root of 21642928 is about 4652.1960405813. The cubic root of 21642928 is about 278.6797024902.

The spelling of 21642928 in words is "twenty-one million, six hundred forty-two thousand, nine hundred twenty-eight".