636778140 has 96 divisors (see below), whose sum is σ = 1838464320. Its totient is φ = 164560896.

The previous prime is 636778139. The next prime is 636778189. The reversal of 636778140 is 41877636.

It is a junction number, because it is equal to n+sod(n) for n = 636778092 and 636778101.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 827676 + ... + 828444.

It is an arithmetic number, because the mean of its divisors is an integer number (19150670).

Almost surely, 2^636778140 is an apocalyptic number.

636778140 is a gapful number since it is divisible by the number (60) 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 636778140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (919232160).

636778140 is an abundant number, since it is smaller than the sum of its proper divisors (1201686180).

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

636778140 is a wasteful number, since it uses less digits than its factorization.

636778140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1191 (or 1189 counting only the distinct ones).

The product of its (nonzero) digits is 169344, while the sum is 42.

The square root of 636778140 is about 25234.4633388547. The cubic root of 636778140 is about 860.3253411216.

It can be divided in two parts, 63677 and 8140, that added together give a palindrome (71817).

The spelling of 636778140 in words is "six hundred thirty-six million, seven hundred seventy-eight thousand, one hundred forty".