20807 has 2 divisors, whose sum is σ = 20808. Its totient is φ = 20806.

The previous prime is 20789. The next prime is 20809. The reversal of 20807 is 70802.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20807 - 2⁶ = 20743 is a prime.

Together with 20809, it forms a pair of twin primes.

It is a Chen prime.

It is an Ulam number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 20807.

It is not a weakly prime, because it can be changed into another prime (20809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10403 + 10404.

It is an arithmetic number, because the mean of its divisors is an integer number (10404).

2²⁰⁸⁰⁷ is an apocalyptic number.

20807 is a deficient number, since it is larger than the sum of its proper divisors (1).

20807 is an equidigital number, since it uses as much as digits as its factorization.

20807 is an odious number, because the sum of its binary digits is odd.

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

The square root of 20807 is about 144.2463171107. The cubic root of 20807 is about 27.5044620859.

The spelling of 20807 in words is "twenty thousand, eight hundred seven".