3635638440 has 128 divisors (see below), whose sum is σ = 12511825920. Its totient is φ = 827884800.

The previous prime is 3635638399. The next prime is 3635638441. The reversal of 3635638440 is 448365363.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 3635638392 and 3635638401.

It is not an unprimeable number, because it can be changed into a prime (3635638441) 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, 219655 + ... + 235625.

It is an arithmetic number, because the mean of its divisors is an integer number (97748640).

Almost surely, 2^3635638440 is an apocalyptic number.

3635638440 is a gapful number since it is divisible by the number (30) 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 3635638440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (6255912960).

3635638440 is an abundant number, since it is smaller than the sum of its proper divisors (8876187480).

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

3635638440 is a wasteful number, since it uses less digits than its factorization.

3635638440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16263 (or 16259 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 42.

The square root of 3635638440 is about 60296.2556051369. The cubic root of 3635638440 is about 1537.6596880870.

The spelling of 3635638440 in words is "three billion, six hundred thirty-five million, six hundred thirty-eight thousand, four hundred forty".