21868560 has 120 divisors (see below), whose sum is σ = 83952960. Its totient is φ = 4997376.

The previous prime is 21868529. The next prime is 21868571. The reversal of 21868560 is 6586812.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (120).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2871 + ... + 7209.

It is an arithmetic number, because the mean of its divisors is an integer number (699608).

Almost surely, 2^21868560 is an apocalyptic number.

21868560 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 21868560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41976480).

21868560 is an abundant number, since it is smaller than the sum of its proper divisors (62084400).

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

21868560 is a wasteful number, since it uses less digits than its factorization.

21868560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4365 (or 4356 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The square root of 21868560 is about 4676.3832178298. The cubic root of 21868560 is about 279.6447876579.

The spelling of 21868560 in words is "twenty-one million, eight hundred sixty-eight thousand, five hundred sixty".