21239360 has 28 divisors (see below), whose sum is σ = 50576988. Its totient is φ = 8495616.

The previous prime is 21239357. The next prime is 21239363. The reversal of 21239360 is 6393212.

It is an interprime number because it is at equal distance from previous prime (21239357) and next prime (21239363).

It can be written as a sum of positive squares in 2 ways, for example, as 15745024 + 5494336 = 3968^2 + 2344^2 .

It is a super-2 number, since 2×21239360² = 902220826419200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21239363) by changing a digit.

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, 32867 + ... + 33506.

It is an arithmetic number, because the mean of its divisors is an integer number (1806321).

Almost surely, 2^21239360 is an apocalyptic number.

21239360 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21239360 is an abundant number, since it is smaller than the sum of its proper divisors (29337628).

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

21239360 is an equidigital number, since it uses as much as digits as its factorization.

21239360 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66390 (or 66380 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 26.

The square root of 21239360 is about 4608.6180141123. The cubic root of 21239360 is about 276.9366761286.

The spelling of 21239360 in words is "twenty-one million, two hundred thirty-nine thousand, three hundred sixty".