1638378637860 has 192 divisors, whose sum is σ = 4848036157440. Its totient is φ = 412583592960.

The previous prime is 1638378637859. The next prime is 1638378637877. The reversal of 1638378637860 is 687368738361.

It is a junction number, because it is equal to n+sod(n) for n = 1638378637791 and 1638378637800.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 83876295 + ... + 83895825.

It is an arithmetic number, because the mean of its divisors is an integer number (25250188320).

Almost surely, 2^{1638378637860} is an apocalyptic number.

1638378637860 is a gapful number since it is divisible by the number (10) 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 1638378637860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2424018078720).

1638378637860 is an abundant number, since it is smaller than the sum of its proper divisors (3209657519580).

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

1638378637860 is a wasteful number, since it uses less digits than its factorization.

1638378637860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20338 (or 20336 counting only the distinct ones).

The product of its (nonzero) digits is 146313216, while the sum is 66.

The spelling of 1638378637860 in words is "one trillion, six hundred thirty-eight billion, three hundred seventy-eight million, six hundred thirty-seven thousand, eight hundred sixty".