20987980 has 48 divisors (see below), whose sum is σ = 48051360. Its totient is φ = 7653888.

The previous prime is 20987971. The next prime is 20988007. The reversal of 20987980 is 8978902.

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, 22687 + ... + 23593.

It is an arithmetic number, because the mean of its divisors is an integer number (1001070).

Almost surely, 2^20987980 is an apocalyptic number.

20987980 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 20987980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24025680).

20987980 is an abundant number, since it is smaller than the sum of its proper divisors (27063380).

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

20987980 is a wasteful number, since it uses less digits than its factorization.

20987980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1018 (or 1016 counting only the distinct ones).

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

The square root of 20987980 is about 4581.2640177139. The cubic root of 20987980 is about 275.8397690702.

The spelling of 20987980 in words is "twenty million, nine hundred eighty-seven thousand, nine hundred eighty".