21431360 has 28 divisors (see below), whose sum is σ = 51034188. Its totient is φ = 8572416.

The previous prime is 21431359. The next prime is 21431383. The reversal of 21431360 is 6313412.

It can be written as a sum of positive squares in 2 ways, for example, as 6190144 + 15241216 = 2488^2 + 3904^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

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, 33167 + ... + 33806.

Almost surely, 2^21431360 is an apocalyptic number.

21431360 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21431360 is an abundant number, since it is smaller than the sum of its proper divisors (29602828).

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

21431360 is an equidigital number, since it uses as much as digits as its factorization.

21431360 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66990 (or 66980 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 20.

The square root of 21431360 is about 4629.4016892035. The cubic root of 21431360 is about 277.7686600859.

Adding to 21431360 its reverse (6313412), we get a palindrome (27744772).

The spelling of 21431360 in words is "twenty-one million, four hundred thirty-one thousand, three hundred sixty".