636864 has 56 divisors (see below), whose sum is σ = 1755648. Its totient is φ = 203520.

The previous prime is 636863. The next prime is 636877. The reversal of 636864 is 468636.

636864 = 262² + 263² + ... + 270².

636864 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (636863) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5899 + ... + 6005.

2⁶³⁶⁸⁶⁴ is an apocalyptic number.

636864 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 636864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (877824).

636864 is an abundant number, since it is smaller than the sum of its proper divisors (1118784).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

636864 is a wasteful number, since it uses less digits than its factorization.

636864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153 (or 143 counting only the distinct ones).

The product of its digits is 20736, while the sum is 33.

The square root of 636864 is about 798.0375930995. The cubic root of 636864 is about 86.0364006715.

The spelling of 636864 in words is "six hundred thirty-six thousand, eight hundred sixty-four".