20909880 has 128 divisors (see below), whose sum is σ = 73440000. Its totient is φ = 5277312.

The previous prime is 20909869. The next prime is 20909893. The reversal of 20909880 is 8890902.

It is a super-2 number, since 2×20909880² = 874446163228800, which contains 22 as substring.

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 31 ways as a sum of consecutive naturals, for example, 20011 + ... + 21029.

It is an arithmetic number, because the mean of its divisors is an integer number (573750).

Almost surely, 2^20909880 is an apocalyptic number.

20909880 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 20909880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36720000).

20909880 is an abundant number, since it is smaller than the sum of its proper divisors (52530120).

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

20909880 is a wasteful number, since it uses less digits than its factorization.

20909880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1058 (or 1048 counting only the distinct ones).

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

The square root of 20909880 is about 4572.7322248301. The cubic root of 20909880 is about 275.4971942055.

The spelling of 20909880 in words is "twenty million, nine hundred nine thousand, eight hundred eighty".