20780 has 12 divisors (see below), whose sum is σ = 43680. Its totient is φ = 8304.

The previous prime is 20773. The next prime is 20789. The reversal of 20780 is 8702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20789) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 500 + ... + 539.

It is an arithmetic number, because the mean of its divisors is an integer number (3640).

2²⁰⁷⁸⁰ is an apocalyptic number.

20780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20780 is an abundant number, since it is smaller than the sum of its proper divisors (22900).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21840).

20780 is a wasteful number, since it uses less digits than its factorization.

20780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1048 (or 1046 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 17.

The square root of 20780 is about 144.1526968183. The cubic root of 20780 is about 27.4925599708.

The spelling of 20780 in words is "twenty thousand, seven hundred eighty".