20779 has 4 divisors (see below), whose sum is σ = 22680. Its totient is φ = 18880.

The previous prime is 20773. The next prime is 20789. The reversal of 20779 is 97702.

20779 = T₃₂ + T₃₃ + ... + T₅₃.

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 20779 - 2³ = 20771 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20771) 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 in 3 ways as a sum of consecutive naturals, for example, 934 + ... + 955.

It is an arithmetic number, because the mean of its divisors is an integer number (5670).

2²⁰⁷⁷⁹ is an apocalyptic number.

20779 is a deficient number, since it is larger than the sum of its proper divisors (1901).

20779 is a wasteful number, since it uses less digits than its factorization.

20779 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1900.

The product of its (nonzero) digits is 882, while the sum is 25.

The square root of 20779 is about 144.1492282324. The cubic root of 20779 is about 27.4921189538.

The spelling of 20779 in words is "twenty thousand, seven hundred seventy-nine".