20740 has 24 divisors (see below), whose sum is σ = 46872. Its totient is φ = 7680.

The previous prime is 20731. The next prime is 20743. The reversal of 20740 is 4702.

It can be written as a sum of positive squares in 4 ways, for example, as 576 + 20164 = 24^2 + 142^2 .

20740 is an undulating number in base 13.

20740 is a modest number, since divided by 740 gives 20 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 20740.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20743) 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, 310 + ... + 370.

It is an arithmetic number, because the mean of its divisors is an integer number (1953).

2²⁰⁷⁴⁰ is an apocalyptic number.

20740 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 20740, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23436).

20740 is an abundant number, since it is smaller than the sum of its proper divisors (26132).

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

20740 is a wasteful number, since it uses less digits than its factorization.

20740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87 (or 85 counting only the distinct ones).

The product of its (nonzero) digits is 56, while the sum is 13.

The square root of 20740 is about 144.0138882192. The cubic root of 20740 is about 27.4749082420.

The spelling of 20740 in words is "twenty thousand, seven hundred forty", and thus it is an iban number.