636839 has 4 divisors (see below), whose sum is σ = 727824. Its totient is φ = 545856.

The previous prime is 636829. The next prime is 636851. The reversal of 636839 is 938636.

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 636839 - 2¹² = 632743 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 636799 and 636808.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (636809) 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, 45482 + ... + 45495.

It is an arithmetic number, because the mean of its divisors is an integer number (181956).

2⁶³⁶⁸³⁹ is an apocalyptic number.

636839 is a deficient number, since it is larger than the sum of its proper divisors (90985).

636839 is an equidigital number, since it uses as much as digits as its factorization.

636839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90984.

The product of its digits is 23328, while the sum is 35.

The square root of 636839 is about 798.0219295232. The cubic root of 636839 is about 86.0352748748.

Subtracting from 636839 its sum of digits (35), we obtain a square (636804 = 798²).

The spelling of 636839 in words is "six hundred thirty-six thousand, eight hundred thirty-nine".