20978980 has 36 divisors (see below), whose sum is σ = 48430620. Its totient is φ = 7627840.

The previous prime is 20978941. The next prime is 20978981. The reversal of 20978980 is 8987902.

It can be written as a sum of positive squares in 2 ways, for example, as 8433216 + 12545764 = 2904^2 + 3542^2 .

It is not an unprimeable number, because it can be changed into a prime (20978981) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1915 + ... + 6754.

It is an arithmetic number, because the mean of its divisors is an integer number (1345295).

Almost surely, 2^20978980 is an apocalyptic number.

20978980 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20978980 is an abundant number, since it is smaller than the sum of its proper divisors (27451640).

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

20978980 is a wasteful number, since it uses less digits than its factorization.

20978980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8700 (or 8687 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 43.

The square root of 20978980 is about 4580.2816507285. The cubic root of 20978980 is about 275.8003351838.

The spelling of 20978980 in words is "twenty million, nine hundred seventy-eight thousand, nine hundred eighty".