636942816640 has 256 divisors, whose sum is σ = 1712734632000. Its totient is φ = 224937934848.

The previous prime is 636942816617. The next prime is 636942816647. The reversal of 636942816640 is 46618249636.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (636942816647) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 18145026 + ... + 18180094.

Almost surely, 2^636942816640 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 636942816640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (856367316000).

636942816640 is an abundant number, since it is smaller than the sum of its proper divisors (1075791815360).

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

636942816640 is a wasteful number, since it uses less digits than its factorization.

636942816640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35197 (or 35185 counting only the distinct ones).

The product of its (nonzero) digits is 8957952, while the sum is 55.

The spelling of 636942816640 in words is "six hundred thirty-six billion, nine hundred forty-two million, eight hundred sixteen thousand, six hundred forty".