21890880 has 168 divisors, whose sum is σ = 82259424. Its totient is φ = 5299200.

The previous prime is 21890879. The next prime is 21890893. The reversal of 21890880 is 8809812.

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

It is a congruent number.

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, 31335 + ... + 32025.

Almost surely, 2^21890880 is an apocalyptic number.

21890880 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 21890880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41129712).

21890880 is an abundant number, since it is smaller than the sum of its proper divisors (60368544).

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

21890880 is a wasteful number, since it uses less digits than its factorization.

21890880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 725 (or 712 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 36.

The square root of 21890880 is about 4678.7690688898. The cubic root of 21890880 is about 279.7398945047.

The spelling of 21890880 in words is "twenty-one million, eight hundred ninety thousand, eight hundred eighty".