20870 has 8 divisors (see below), whose sum is σ = 37584. Its totient is φ = 8344.

The previous prime is 20857. The next prime is 20873. The reversal of 20870 is 7802.

It is a sphenic number, since it is the product of 3 distinct primes.

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 (20873) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1034 + ... + 1053.

It is an arithmetic number, because the mean of its divisors is an integer number (4698).

2²⁰⁸⁷⁰ is an apocalyptic number.

20870 is a deficient number, since it is larger than the sum of its proper divisors (16714).

20870 is a wasteful number, since it uses less digits than its factorization.

20870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2094.

The product of its (nonzero) digits is 112, while the sum is 17.

The square root of 20870 is about 144.4645285182. The cubic root of 20870 is about 27.5321937017.

The spelling of 20870 in words is "twenty thousand, eight hundred seventy".