1981100000 has 144 divisors (see below), whose sum is σ = 5321190672. Its totient is φ = 720000000.

The previous prime is 1981099993. The next prime is 1981100021. The reversal of 1981100000 is 11891.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1099100 + ... + 1100900.

It is an arithmetic number, because the mean of its divisors is an integer number (36952713).

Almost surely, 2^1981100000 is an apocalyptic number.

1981100000 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 1981100000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2660595336).

1981100000 is an abundant number, since it is smaller than the sum of its proper divisors (3340090672).

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

1981100000 is an equidigital number, since it uses as much as digits as its factorization.

1981100000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1847 (or 1819 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 20.

The square root of 1981100000 is about 44509.5495371499. The cubic root of 1981100000 is about 1255.9397309715.

Adding to 1981100000 its reverse (11891), we get a palindrome (1981111891).

The spelling of 1981100000 in words is "one billion, nine hundred eighty-one million, one hundred thousand".