20783857 has 4 divisors (see below), whose sum is σ = 21454336. Its totient is φ = 20113380.

The previous prime is 20783839. The next prime is 20783879. The reversal of 20783857 is 75838702.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20783857 - 2¹⁵ = 20751089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20783827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 335193 + ... + 335254.

It is an arithmetic number, because the mean of its divisors is an integer number (5363584).

Almost surely, 2^20783857 is an apocalyptic number.

It is an amenable number.

20783857 is a deficient number, since it is larger than the sum of its proper divisors (670479).

20783857 is an equidigital number, since it uses as much as digits as its factorization.

20783857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 670478.

The product of its (nonzero) digits is 94080, while the sum is 40.

The square root of 20783857 is about 4558.9315634258. The cubic root of 20783857 is about 274.9426084091.

The spelling of 20783857 in words is "twenty million, seven hundred eighty-three thousand, eight hundred fifty-seven".