636861312 has 128 divisors (see below), whose sum is σ = 1895731200. Its totient is φ = 210470400.

The previous prime is 636861311. The next prime is 636861317. The reversal of 636861312 is 213168636.

636861312 is a `hidden beast` number, since 6 + 36 + 8 + 613 + 1 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (128).

It is a super-2 number, since 2×636861312² = 811184661444722688, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

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 (636861311) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 438187 + ... + 439637.

It is an arithmetic number, because the mean of its divisors is an integer number (14810400).

Almost surely, 2^636861312 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 636861312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (947865600).

636861312 is an abundant number, since it is smaller than the sum of its proper divisors (1258869888).

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

636861312 is a wasteful number, since it uses less digits than its factorization.

636861312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1601 (or 1583 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 636861312 is about 25236.1112693695. Note that the first 3 decimals coincide. The cubic root of 636861312 is about 860.3627962726.

The spelling of 636861312 in words is "six hundred thirty-six million, eight hundred sixty-one thousand, three hundred twelve".