21431328 has 24 divisors (see below), whose sum is σ = 56257488. Its totient is φ = 7143744.

The previous prime is 21431317. The next prime is 21431341. The reversal of 21431328 is 82313412.

It is a tau number, because it is divible by the number of its divisors (24).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 21431298 and 21431307.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111526 + ... + 111717.

It is an arithmetic number, because the mean of its divisors is an integer number (2344062).

Almost surely, 2^21431328 is an apocalyptic number.

It is an amenable number.

21431328 is an abundant number, since it is smaller than the sum of its proper divisors (34826160).

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

21431328 is a wasteful number, since it uses less digits than its factorization.

21431328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 223256 (or 223248 counting only the distinct ones).

The product of its digits is 1152, while the sum is 24.

The square root of 21431328 is about 4629.3982330320. The cubic root of 21431328 is about 277.7685218368.

The spelling of 21431328 in words is "twenty-one million, four hundred thirty-one thousand, three hundred twenty-eight".