20856783 has 4 divisors (see below), whose sum is σ = 27809048. Its totient is φ = 13904520.

The previous prime is 20856751. The next prime is 20856793. The reversal of 20856783 is 38765802.

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

It is not a de Polignac number, because 20856783 - 2⁵ = 20856751 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20856733) 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, 3476128 + ... + 3476133.

It is an arithmetic number, because the mean of its divisors is an integer number (6952262).

Almost surely, 2^20856783 is an apocalyptic number.

20856783 is a deficient number, since it is larger than the sum of its proper divisors (6952265).

20856783 is an equidigital number, since it uses as much as digits as its factorization.

20856783 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6952264.

The product of its (nonzero) digits is 80640, while the sum is 39.

The square root of 20856783 is about 4566.9227057177. The cubic root of 20856783 is about 275.2638041552.

The spelling of 20856783 in words is "twenty million, eight hundred fifty-six thousand, seven hundred eighty-three".