20500 has 24 divisors (see below), whose sum is σ = 45864. Its totient is φ = 8000.

The previous prime is 20483. The next prime is 20507. The reversal of 20500 is 502.

It can be written as a sum of positive squares in 4 ways, for example, as 4624 + 15876 = 68^2 + 126^2 .

It is a sliding number, since 20500 = 500 + 20000 and 1/500 + 1/20000 = 0.0020500.

It is a plaindrome in base 11.

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20507) by changing a digit.

20500 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 480 + ... + 520.

It is an arithmetic number, because the mean of its divisors is an integer number (1911).

2²⁰⁵⁰⁰ is an apocalyptic number.

20500 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 20500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22932).

20500 is an abundant number, since it is smaller than the sum of its proper divisors (25364).

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

20500 is a wasteful number, since it uses less digits than its factorization.

20500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60 (or 48 counting only the distinct ones).

The product of its (nonzero) digits is 10, while the sum is 7.

The square root of 20500 is about 143.1782106328. The cubic root of 20500 is about 27.3685183740.

It can be divided in two parts, 20 and 500, that multiplied together give a 4-th power (10000 = 10⁴).

The spelling of 20500 in words is "twenty thousand, five hundred".