20671 has 4 divisors (see below), whose sum is σ = 23632. Its totient is φ = 17712.

The previous prime is 20663. The next prime is 20681. The reversal of 20671 is 17602.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20671 - 2³ = 20663 is a prime.

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 (20611) 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, 1470 + ... + 1483.

It is an arithmetic number, because the mean of its divisors is an integer number (5908).

2²⁰⁶⁷¹ is an apocalyptic number.

20671 is a deficient number, since it is larger than the sum of its proper divisors (2961).

20671 is an equidigital number, since it uses as much as digits as its factorization.

20671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2960.

The product of its (nonzero) digits is 84, while the sum is 16.

The square root of 20671 is about 143.7741284098. The cubic root of 20671 is about 27.4444055916. Note that the first 4 decimals are identical.

The spelling of 20671 in words is "twenty thousand, six hundred seventy-one".