20780785 has 4 divisors (see below), whose sum is σ = 24936948. Its totient is φ = 16624624.

The previous prime is 20780779. The next prime is 20780797. The reversal of 20780785 is 58708702.

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

It can be written as a sum of positive squares in 2 ways, for example, as 2187441 + 18593344 = 1479^2 + 4312^2 .

It is a cyclic number.

It is not a de Polignac number, because 20780785 - 2⁷ = 20780657 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2078074 + ... + 2078083.

It is an arithmetic number, because the mean of its divisors is an integer number (6234237).

Almost surely, 2^20780785 is an apocalyptic number.

It is an amenable number.

20780785 is a deficient number, since it is larger than the sum of its proper divisors (4156163).

20780785 is an equidigital number, since it uses as much as digits as its factorization.

20780785 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4156162.

The product of its (nonzero) digits is 31360, while the sum is 37.

The square root of 20780785 is about 4558.5946299271. The cubic root of 20780785 is about 274.9290615923.

The spelling of 20780785 in words is "twenty million, seven hundred eighty thousand, seven hundred eighty-five".