21388360 has 32 divisors (see below), whose sum is σ = 54999360. Its totient is φ = 7333056.

The previous prime is 21388333. The next prime is 21388373. The reversal of 21388360 is 6388312.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 37914 + ... + 38473.

It is an arithmetic number, because the mean of its divisors is an integer number (1718730).

Almost surely, 2^21388360 is an apocalyptic number.

21388360 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21388360 is an abundant number, since it is smaller than the sum of its proper divisors (33611000).

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

21388360 is a wasteful number, since it uses less digits than its factorization.

21388360 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76405 (or 76401 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 21388360 is about 4624.7551286528. The cubic root of 21388360 is about 277.5827635072.

The spelling of 21388360 in words is "twenty-one million, three hundred eighty-eight thousand, three hundred sixty".