1998001981836 has 288 divisors, whose sum is σ = 6133662080000. Its totient is φ = 535686649344.

The previous prime is 1998001981751. The next prime is 1998001981837. The reversal of 1998001981836 is 6381891008991.

1998001981836 is a `hidden beast` number, since 199 + 80 + 0 + 198 + 183 + 6 = 666.

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

It is not an unprimeable number, because it can be changed into a prime (1998001981837) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 218189370 + ... + 218198526.

Almost surely, 2^{1998001981836} 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 1998001981836, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3066831040000).

1998001981836 is an abundant number, since it is smaller than the sum of its proper divisors (4135660098164).

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

1998001981836 is a wasteful number, since it uses less digits than its factorization.

1998001981836 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9621 (or 9616 counting only the distinct ones).

The product of its (nonzero) digits is 6718464, while the sum is 63.

The spelling of 1998001981836 in words is "one trillion, nine hundred ninety-eight billion, one million, nine hundred eighty-one thousand, eight hundred thirty-six".