21543928 has 24 divisors (see below), whose sum is σ = 46990800. Its totient is φ = 9232944.

The previous prime is 21543923. The next prime is 21543931. The reversal of 21543928 is 82934512.

It is a junction number, because it is equal to n+sod(n) for n = 21543893 and 21543902.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21543923) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 27088 + ... + 27871.

It is an arithmetic number, because the mean of its divisors is an integer number (1957950).

Almost surely, 2^21543928 is an apocalyptic number.

21543928 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21543928 is an abundant number, since it is smaller than the sum of its proper divisors (25446872).

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

21543928 is a wasteful number, since it uses less digits than its factorization.

21543928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54979 (or 54968 counting only the distinct ones).

The product of its digits is 17280, while the sum is 34.

The square root of 21543928 is about 4641.5437087245. The cubic root of 21543928 is about 278.2541367738.

The spelling of 21543928 in words is "twenty-one million, five hundred forty-three thousand, nine hundred twenty-eight".