21986560 has 72 divisors (see below), whose sum is σ = 53532360. Its totient is φ = 8650752.

The previous prime is 21986543. The next prime is 21986563. The reversal of 21986560 is 6568912.

It can be written as a sum of positive squares in 4 ways, for example, as 9216 + 21977344 = 96^2 + 4688^2 .

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21986563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 113824 + ... + 114016.

It is an arithmetic number, because the mean of its divisors is an integer number (743505).

Almost surely, 2^21986560 is an apocalyptic number.

21986560 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 21986560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26766180).

21986560 is an abundant number, since it is smaller than the sum of its proper divisors (31545800).

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

21986560 is an equidigital number, since it uses as much as digits as its factorization.

21986560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 303 (or 289 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 37.

The square root of 21986560 is about 4688.9828321289. The cubic root of 21986560 is about 280.1468617322.

The spelling of 21986560 in words is "twenty-one million, nine hundred eighty-six thousand, five hundred sixty".