20980980 has 72 divisors (see below), whose sum is σ = 64045800. Its totient is φ = 5559552.

The previous prime is 20980957. The next prime is 20980987. The reversal of 20980980 is 8908902.

It can be written as a sum of positive squares in 4 ways, for example, as 9771876 + 11209104 = 3126^2 + 3348^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20980987) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 40966 + ... + 41474.

It is an arithmetic number, because the mean of its divisors is an integer number (889525).

Almost surely, 2^20980980 is an apocalyptic number.

20980980 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is a pronic number, being equal to 4580×4581.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20980980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32022900).

20980980 is an abundant number, since it is smaller than the sum of its proper divisors (43064820).

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

20980980 is a wasteful number, since it uses less digits than its factorization.

20980980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 753 (or 748 counting only the distinct ones).

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

The square root of 20980980 is about 4580.4999727104. The cubic root of 20980980 is about 275.8090992442.

The spelling of 20980980 in words is "twenty million, nine hundred eighty thousand, nine hundred eighty".