20872 has 8 divisors (see below), whose sum is σ = 39150. Its totient is φ = 10432.

The previous prime is 20857. The next prime is 20873. The reversal of 20872 is 27802.

It can be written as a sum of positive squares in only one way, i.e., 17956 + 2916 = 134^2 + 54^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a hoax number, since the sum of its digits (19) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (20873) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1297 + ... + 1312.

2²⁰⁸⁷² is an apocalyptic number.

It is an amenable number.

20872 is a deficient number, since it is larger than the sum of its proper divisors (18278).

20872 is a wasteful number, since it uses less digits than its factorization.

20872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2615 (or 2611 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 19.

The square root of 20872 is about 144.4714504669. The cubic root of 20872 is about 27.5330731559.

The spelling of 20872 in words is "twenty thousand, eight hundred seventy-two".