20779807 has 4 divisors (see below), whose sum is σ = 20871576. Its totient is φ = 20688040.

The previous prime is 20779799. The next prime is 20779823. The reversal of 20779807 is 70897702.

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 20779807 - 2³ = 20779799 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20779807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20779877) 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, 45544 + ... + 45997.

It is an arithmetic number, because the mean of its divisors is an integer number (5217894).

Almost surely, 2^20779807 is an apocalyptic number.

20779807 is a deficient number, since it is larger than the sum of its proper divisors (91769).

20779807 is an equidigital number, since it uses as much as digits as its factorization.

20779807 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91768.

The product of its (nonzero) digits is 49392, while the sum is 40.

The square root of 20779807 is about 4558.4873587628. The cubic root of 20779807 is about 274.9247485560.

The spelling of 20779807 in words is "twenty million, seven hundred seventy-nine thousand, eight hundred seven".