21312360 has 96 divisors (see below), whose sum is σ = 70635240. Its totient is φ = 5571072.

The previous prime is 21312341. The next prime is 21312427. The reversal of 21312360 is 6321312.

It can be written as a sum of positive squares in 4 ways, for example, as 13793796 + 7518564 = 3714^2 + 2742^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18522 + ... + 19638.

Almost surely, 2^21312360 is an apocalyptic number.

21312360 is a gapful number since it is divisible by the number (20) 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 21312360, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35317620).

21312360 is an abundant number, since it is smaller than the sum of its proper divisors (49322880).

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

21312360 is a wasteful number, since it uses less digits than its factorization.

21312360 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1187 (or 1180 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 21312360 is about 4616.5311652798. The cubic root of 21312360 is about 277.2535918321.

Adding to 21312360 its reverse (6321312), we get a palindrome (27633672).

The spelling of 21312360 in words is "twenty-one million, three hundred twelve thousand, three hundred sixty".