20779785 has 24 divisors (see below), whose sum is σ = 38790024. Its totient is φ = 10229760.

The previous prime is 20779769. The next prime is 20779789. The reversal of 20779785 is 58797702.

It can be written as a sum of positive squares in 4 ways, for example, as 2143296 + 18636489 = 1464^2 + 4317^2 .

It is not a de Polignac number, because 20779785 - 2⁴ = 20779769 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20779785.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20779789) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17176 + ... + 18345.

It is an arithmetic number, because the mean of its divisors is an integer number (1616251).

Almost surely, 2^20779785 is an apocalyptic number.

It is an amenable number.

20779785 is a deficient number, since it is larger than the sum of its proper divisors (18010239).

20779785 is a wasteful number, since it uses less digits than its factorization.

20779785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35545 (or 35542 counting only the distinct ones).

The product of its (nonzero) digits is 246960, while the sum is 45.

The square root of 20779785 is about 4558.4849456810. The cubic root of 20779785 is about 274.9246515331.

The spelling of 20779785 in words is "twenty million, seven hundred seventy-nine thousand, seven hundred eighty-five".