21808960 has 112 divisors (see below), whose sum is σ = 58155840. Its totient is φ = 7741440.

The previous prime is 21808939. The next prime is 21808967. The reversal of 21808960 is 6980812.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21808967) 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, 103255 + ... + 103465.

Almost surely, 2^21808960 is an apocalyptic number.

21808960 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 21808960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29077920).

21808960 is an abundant number, since it is smaller than the sum of its proper divisors (36346880).

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

21808960 is a wasteful number, since it uses less digits than its factorization.

21808960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 264 (or 254 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 34.

The square root of 21808960 is about 4670.0064239785. The cubic root of 21808960 is about 279.3905109943.

The spelling of 21808960 in words is "twenty-one million, eight hundred eight thousand, nine hundred sixty".