20990880 has 192 divisors, whose sum is σ = 75841920. Its totient is φ = 5419008.

The previous prime is 20990863. The next prime is 20990891. The reversal of 20990880 is 8809902.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its 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 31 ways as a sum of consecutive naturals, for example, 185704 + ... + 185816.

It is an arithmetic number, because the mean of its divisors is an integer number (395010).

Almost surely, 2^20990880 is an apocalyptic number.

20990880 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 20990880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37920960).

20990880 is an abundant number, since it is smaller than the sum of its proper divisors (54851040).

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

20990880 is a wasteful number, since it uses less digits than its factorization.

20990880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180 (or 166 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 20990880 is about 4581.5805133163. The cubic root of 20990880 is about 275.8524731432.

The spelling of 20990880 in words is "twenty million, nine hundred ninety thousand, eight hundred eighty".