21668880 has 160 divisors (see below), whose sum is σ = 73281024. Its totient is φ = 5275648.

The previous prime is 21668851. The next prime is 21668917. The reversal of 21668880 is 8886612.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 191704 + ... + 191816.

Almost surely, 2^21668880 is an apocalyptic number.

21668880 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 21668880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36640512).

21668880 is an abundant number, since it is smaller than the sum of its proper divisors (51612144).

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

21668880 is a wasteful number, since it uses less digits than its factorization.

21668880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 193 (or 187 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 39.

The square root of 21668880 is about 4654.9844253230. The cubic root of 21668880 is about 278.7910461251.

It can be divided in two parts, 216 and 68880, that added together give a palindrome (69096).

The spelling of 21668880 in words is "twenty-one million, six hundred sixty-eight thousand, eight hundred eighty".