20660 has 12 divisors (see below), whose sum is σ = 43428. Its totient is φ = 8256.

The previous prime is 20641. The next prime is 20663. The reversal of 20660 is 6602.

20660 = T₁₀ + T₁₁ + ... + T₄₉.

It can be written as a sum of positive squares in 2 ways, for example, as 14884 + 5776 = 122^2 + 76^2 .

It is a hoax number, since the sum of its digits (14) coincides with the sum of the digits of its distinct prime factors.

It is a nialpdrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20663) by changing a digit.

20660 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 3 ways as a sum of consecutive naturals, for example, 497 + ... + 536.

It is an arithmetic number, because the mean of its divisors is an integer number (3619).

2²⁰⁶⁶⁰ is an apocalyptic number.

20660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20660 is an abundant number, since it is smaller than the sum of its proper divisors (22768).

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 (21714).

20660 is a wasteful number, since it uses less digits than its factorization.

20660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1042 (or 1040 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 20660 is about 143.7358688706. The cubic root of 20660 is about 27.4395365798.

The spelling of 20660 in words is "twenty thousand, six hundred sixty".