636401808 has 360 divisors, whose sum is σ = 2249320320. Its totient is φ = 166924800.

The previous prime is 636401807. The next prime is 636401819. The reversal of 636401808 is 808104636.

It is a happy number.

636401808 is a `hidden beast` number, since 6 + 3 + 640 + 1 + 8 + 0 + 8 = 666.

636401808 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×636401808² = 810014522451337728, which contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (636401807) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 6300958 + ... + 6301058.

It is an arithmetic number, because the mean of its divisors is an integer number (6248112).

Almost surely, 2^636401808 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 636401808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1124660160).

636401808 is an abundant number, since it is smaller than the sum of its proper divisors (1612918512).

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

636401808 is a wasteful number, since it uses less digits than its factorization.

636401808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 195 (or 179 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 36.

The square root of 636401808 is about 25227.0055297889. The cubic root of 636401808 is about 860.1558253785.

The spelling of 636401808 in words is "six hundred thirty-six million, four hundred one thousand, eight hundred eight".