1998400000 has 120 divisors (see below), whose sum is σ = 4994797500. Its totient is φ = 798720000.

The previous prime is 1998399979. The next prime is 1998400013. The reversal of 1998400000 is 48991.

It can be written as a sum of positive squares in 6 ways, for example, as 303595776 + 1694804224 = 17424^2 + 41168^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1599376 + ... + 1600624.

Almost surely, 2^1998400000 is an apocalyptic number.

1998400000 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 1998400000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2497398750).

1998400000 is an abundant number, since it is smaller than the sum of its proper divisors (2996397500).

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

1998400000 is an frugal number, since it uses more digits than its factorization.

1998400000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1292 (or 1256 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 1998400000 is about 44703.4674270352. The cubic root of 1998400000 is about 1259.5849813140.

Adding to 1998400000 its reverse (48991), we get a palindrome (1998448991).

The spelling of 1998400000 in words is "one billion, nine hundred ninety-eight million, four hundred thousand".