1989999900 has 216 divisors, whose sum is σ = 7393276800. Its totient is φ = 454818240.

The previous prime is 1989999899. The next prime is 1989999917. The reversal of 1989999900 is 99999891.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 164251 + ... + 175949.

Almost surely, 2^1989999900 is an apocalyptic number.

1989999900 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 1989999900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3696638400).

1989999900 is an abundant number, since it is smaller than the sum of its proper divisors (5403276900).

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

1989999900 is a wasteful number, since it uses less digits than its factorization.

1989999900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11735 (or 11716 counting only the distinct ones).

The product of its (nonzero) digits is 4251528, while the sum is 63.

The square root of 1989999900 is about 44609.4149255513. The cubic root of 1989999900 is about 1257.8176508746.

The spelling of 1989999900 in words is "one billion, nine hundred eighty-nine million, nine hundred ninety-nine thousand, nine hundred".