1638849785568 has 96 divisors (see below), whose sum is σ = 4533217799040. Its totient is φ = 516980989440.

The previous prime is 1638849785567. The next prime is 1638849785579. The reversal of 1638849785568 is 8655879488361.

It is a tau number, because it is divible by the number of its divisors (96).

It is a junction number, because it is equal to n+sod(n) for n = 1638849785493 and 1638849785502.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1638849785563) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1238971 + ... + 2193797.

It is an arithmetic number, because the mean of its divisors is an integer number (47221018740).

Almost surely, 2^{1638849785568} 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 1638849785568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2266608899520).

1638849785568 is an abundant number, since it is smaller than the sum of its proper divisors (2894368013472).

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

1638849785568 is a wasteful number, since it uses less digits than its factorization.

1638849785568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 955800 (or 955792 counting only the distinct ones).

The product of its digits is 2786918400, while the sum is 78.

The spelling of 1638849785568 in words is "one trillion, six hundred thirty-eight billion, eight hundred forty-nine million, seven hundred eighty-five thousand, five hundred sixty-eight".