1998561320 has 128 divisors (see below), whose sum is σ = 5336893440. Its totient is φ = 659128320.

The previous prime is 1998561317. The next prime is 1998561329. The reversal of 1998561320 is 231658991.

It is a happy number.

1998561320 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (1998561329) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1674644 + ... + 1675836.

It is an arithmetic number, because the mean of its divisors is an integer number (41694480).

Almost surely, 2^1998561320 is an apocalyptic number.

1998561320 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 1998561320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2668446720).

1998561320 is an abundant number, since it is smaller than the sum of its proper divisors (3338332120).

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

1998561320 is a wasteful number, since it uses less digits than its factorization.

1998561320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1435 (or 1431 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 44.

The square root of 1998561320 is about 44705.2717249319. The cubic root of 1998561320 is about 1259.6188735581.

The spelling of 1998561320 in words is "one billion, nine hundred ninety-eight million, five hundred sixty-one thousand, three hundred twenty".