1998944438400 has 3456 divisors, whose sum is σ = 9554047251840. Its totient is φ = 403705036800.

The previous prime is 1998944438321. The next prime is 1998944438401. The reversal of 1998944438400 is 48344498991.

1998944438400 is a `hidden beast` number, since 19 + 98 + 94 + 4 + 43 + 8 + 400 = 666.

It is a tau number, because it is divible by the number of its divisors (3456).

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

It is not an unprimeable number, because it can be changed into a prime (1998944438401) by changing a digit.

It is a polite number, since it can be written in 431 ways as a sum of consecutive naturals, for example, 37715932774 + ... + 37715932826.

It is an arithmetic number, because the mean of its divisors is an integer number (2764481265).

Almost surely, 2^{1998944438400} is an apocalyptic number.

1998944438400 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 1998944438400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4777023625920).

1998944438400 is an abundant number, since it is smaller than the sum of its proper divisors (7555102813440).

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

1998944438400 is a wasteful number, since it uses less digits than its factorization.

1998944438400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166 (or 124 counting only the distinct ones).

The product of its (nonzero) digits is 35831808, while the sum is 63.

The spelling of 1998944438400 in words is "one trillion, nine hundred ninety-eight billion, nine hundred forty-four million, four hundred thirty-eight thousand, four hundred".