1998138808512 has 1680 divisors, whose sum is σ = 8028743627520. Its totient is φ = 479384801280.

The previous prime is 1998138808483. The next prime is 1998138808513. The reversal of 1998138808512 is 2158088318991.

1998138808512 is a `hidden beast` number, since 1 + 9 + 9 + 8 + 1 + 38 + 80 + 8 + 512 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a self number, because there is not a number n which added to its sum of digits gives 1998138808512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1998138808513) by changing a digit.

It is a polite number, since it can be written in 239 ways as a sum of consecutive naturals, for example, 3587322538 + ... + 3587323094.

It is an arithmetic number, because the mean of its divisors is an integer number (4779014064).

Almost surely, 2^{1998138808512} is an apocalyptic number.

1998138808512 is a gapful number since it is divisible by the number (12) 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 1998138808512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4014371813760).

1998138808512 is an abundant number, since it is smaller than the sum of its proper divisors (6030604819008).

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

1998138808512 is a wasteful number, since it uses less digits than its factorization.

1998138808512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 672 (or 642 counting only the distinct ones).

The product of its (nonzero) digits is 9953280, while the sum is 63.

The spelling of 1998138808512 in words is "one trillion, nine hundred ninety-eight billion, one hundred thirty-eight million, eight hundred eight thousand, five hundred twelve".