21321360 has 80 divisors (see below), whose sum is σ = 73447680. Its totient is φ = 5685120.

The previous prime is 21321359. The next prime is 21321367. The reversal of 21321360 is 6312312.

It is a tau number, because it is divible by the number of its divisors (80).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321367) 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, 2776 + ... + 7095.

It is an arithmetic number, because the mean of its divisors is an integer number (918096).

Almost surely, 2^21321360 is an apocalyptic number.

21321360 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21321360 is an abundant number, since it is smaller than the sum of its proper divisors (52126320).

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

21321360 is a wasteful number, since it uses less digits than its factorization.

21321360 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9893 (or 9881 counting only the distinct ones).

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

The square root of 21321360 is about 4617.5058202454. The cubic root of 21321360 is about 277.2926134948.

Adding to 21321360 its reverse (6312312), we get a palindrome (27633672).

The spelling of 21321360 in words is "twenty-one million, three hundred twenty-one thousand, three hundred sixty".