1998978432 has 128 divisors (see below), whose sum is σ = 5916326400. Its totient is φ = 592803840.

The previous prime is 1998978419. The next prime is 1998978437. The reversal of 1998978432 is 2348798991.

It is a tau number, because it is divible by the number of its divisors (128).

It is a super-3 number, since 3×1998978432³ (a number of 29 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1998978437) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 193494 + ... + 203562.

It is an arithmetic number, because the mean of its divisors is an integer number (46221300).

Almost surely, 2^1998978432 is an apocalyptic number.

1998978432 is a gapful number since it is divisible by the number (12) 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 1998978432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2958163200).

1998978432 is an abundant number, since it is smaller than the sum of its proper divisors (3917347968).

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

1998978432 is a wasteful number, since it uses less digits than its factorization.

1998978432 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10144 (or 10132 counting only the distinct ones).

The product of its digits is 7838208, while the sum is 60.

The square root of 1998978432 is about 44709.9366136880. The cubic root of 1998978432 is about 1259.7064975229.

The spelling of 1998978432 in words is "one billion, nine hundred ninety-eight million, nine hundred seventy-eight thousand, four hundred thirty-two".