636919640 has 96 divisors (see below), whose sum is σ = 1683173520. Its totient is φ = 216260352.

The previous prime is 636919627. The next prime is 636919643. The reversal of 636919640 is 46919636.

It is a junction number, because it is equal to n+sod(n) for n = 636919591 and 636919600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (636919643) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 208202 + ... + 211238.

Almost surely, 2^636919640 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 636919640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (841586760).

636919640 is an abundant number, since it is smaller than the sum of its proper divisors (1046253880).

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

636919640 is a wasteful number, since it uses less digits than its factorization.

636919640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3169 (or 3158 counting only the distinct ones).

The product of its (nonzero) digits is 209952, while the sum is 44.

The square root of 636919640 is about 25237.2668884727. The cubic root of 636919640 is about 860.3890613889.

The spelling of 636919640 in words is "six hundred thirty-six million, nine hundred nineteen thousand, six hundred forty".