20540 has 24 divisors (see below), whose sum is σ = 47040. Its totient is φ = 7488.

The previous prime is 20533. The next prime is 20543. The reversal of 20540 is 4502.

20540 = 1² + 2² + ... + 39².

20540 is a modest number, since divided by 540 gives 20 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20543) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 221 + ... + 299.

It is an arithmetic number, because the mean of its divisors is an integer number (1960).

2²⁰⁵⁴⁰ is an apocalyptic number.

20540 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 20540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23520).

20540 is an abundant number, since it is smaller than the sum of its proper divisors (26500).

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

20540 is a wasteful number, since it uses less digits than its factorization.

20540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101 (or 99 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 11.

The square root of 20540 is about 143.3178286188. The cubic root of 20540 is about 27.3863074712.

The spelling of 20540 in words is "twenty thousand, five hundred forty".