20940 has 24 divisors (see below), whose sum is σ = 58800. Its totient is φ = 5568.

The previous prime is 20939. The next prime is 20947. The reversal of 20940 is 4902.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a nialpdrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (20947) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 115 + ... + 234.

It is an arithmetic number, because the mean of its divisors is an integer number (2450).

2²⁰⁹⁴⁰ is an apocalyptic number.

20940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20940 is an abundant number, since it is smaller than the sum of its proper divisors (37860).

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 (29400).

20940 is a wasteful number, since it uses less digits than its factorization.

20940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 361 (or 359 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 15.

The square root of 20940 is about 144.7065997113. The cubic root of 20940 is about 27.5629412314.

Adding to 20940 its product of nonzero digits (72), we get a palindrome (21012).

The spelling of 20940 in words is "twenty thousand, nine hundred forty".