21293328 has 80 divisors (see below), whose sum is σ = 63488000. Its totient is φ = 6023808.

The previous prime is 21293317. The next prime is 21293329. The reversal of 21293328 is 82339212.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21293295 and 21293304.

It is not an unprimeable number, because it can be changed into a prime (21293329) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42423 + ... + 42921.

It is an arithmetic number, because the mean of its divisors is an integer number (793600).

Almost surely, 2^21293328 is an apocalyptic number.

21293328 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21293328, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31744000).

21293328 is an abundant number, since it is smaller than the sum of its proper divisors (42194672).

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

21293328 is a wasteful number, since it uses less digits than its factorization.

21293328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 644 (or 638 counting only the distinct ones).

The product of its digits is 5184, while the sum is 30.

The square root of 21293328 is about 4614.4694169536. The cubic root of 21293328 is about 277.1710378300.

The spelling of 21293328 in words is "twenty-one million, two hundred ninety-three thousand, three hundred twenty-eight".