1981318500 has 288 divisors, whose sum is σ = 7377377280. Its totient is φ = 438048000.

The previous prime is 1981318459. The next prime is 1981318501. The reversal of 1981318500 is 58131891.

1981318500 is a `hidden beast` number, since 19 + 8 + 131 + 8 + 500 = 666.

It is a super-3 number, since 3×1981318500³ (a number of 29 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (1981318501) by changing a digit.

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 95 ways as a sum of consecutive naturals, for example, 975486 + ... + 977514.

Almost surely, 2^1981318500 is an apocalyptic number.

1981318500 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 1981318500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3688688640).

1981318500 is an abundant number, since it is smaller than the sum of its proper divisors (5396058780).

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

1981318500 is a wasteful number, since it uses less digits than its factorization.

1981318500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2092 (or 2077 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 36.

The square root of 1981318500 is about 44512.0039989215. The cubic root of 1981318500 is about 1255.9859027520.

The spelling of 1981318500 in words is "one billion, nine hundred eighty-one million, three hundred eighteen thousand, five hundred".