20912880 has 80 divisors (see below), whose sum is σ = 65710080. Its totient is φ = 5501184.

The previous prime is 20912833. The next prime is 20912891. The reversal of 20912880 is 8821902.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18409 + ... + 19511.

It is an arithmetic number, because the mean of its divisors is an integer number (821376).

Almost surely, 2^20912880 is an apocalyptic number.

20912880 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 20912880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32855040).

20912880 is an abundant number, since it is smaller than the sum of its proper divisors (44797200).

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

20912880 is a wasteful number, since it uses less digits than its factorization.

20912880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1198 (or 1192 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 30.

The square root of 20912880 is about 4573.0602445190. The cubic root of 20912880 is about 275.5103690310.

The spelling of 20912880 in words is "twenty million, nine hundred twelve thousand, eight hundred eighty".