1001998991988 has 144 divisors (see below), whose sum is σ = 2687630400000. Its totient is φ = 313877830464.

The previous prime is 1001998991971. The next prime is 1001998992013. The reversal of 1001998991988 is 8891998991001.

1001998991988 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 56990983 + ... + 57008561.

It is an arithmetic number, because the mean of its divisors is an integer number (18664100000).

Almost surely, 2^{1001998991988} is an apocalyptic number.

1001998991988 is a gapful number since it is divisible by the number (18) 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 1001998991988, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1343815200000).

1001998991988 is an abundant number, since it is smaller than the sum of its proper divisors (1685631408012).

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

1001998991988 is a wasteful number, since it uses less digits than its factorization.

1001998991988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18274 (or 18269 counting only the distinct ones).

The product of its (nonzero) digits is 30233088, while the sum is 72.

The spelling of 1001998991988 in words is "one trillion, one billion, nine hundred ninety-eight million, nine hundred ninety-one thousand, nine hundred eighty-eight".