1981223193600 has 3960 divisors, whose sum is σ = 9579566189952. Its totient is φ = 401316249600.

The previous prime is 1981223193589. The next prime is 1981223193647. The reversal of 1981223193600 is 63913221891.

It is a happy number.

1981223193600 is a `hidden beast` number, since 1 + 9 + 8 + 1 + 2 + 2 + 31 + 9 + 3 + 600 = 666.

It is a super-3 number, since 3×1981223193600³ (a number of 38 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 359 ways as a sum of consecutive naturals, for example, 53546572782 + ... + 53546572818.

Almost surely, 2^{1981223193600} is an apocalyptic number.

1981223193600 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 1981223193600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4789783094976).

1981223193600 is an abundant number, since it is smaller than the sum of its proper divisors (7598342996352).

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

1981223193600 is a wasteful number, since it uses less digits than its factorization.

1981223193600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141 (or 102 counting only the distinct ones).

The product of its (nonzero) digits is 139968, while the sum is 45.

The spelling of 1981223193600 in words is "one trillion, nine hundred eighty-one billion, two hundred twenty-three million, one hundred ninety-three thousand, six hundred".