81518994000 has 640 divisors, whose sum is σ = 300280780800. Its totient is φ = 21134131200.

The previous prime is 81518993993. The next prime is 81518994013. The reversal of 81518994000 is 49981518.

81518994000 is a `hidden beast` number, since 8 + 1 + 518 + 99 + 40 + 0 + 0 = 666.

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

It is a congruent number.

It is an unprimeable number.

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 127 ways as a sum of consecutive naturals, for example, 413801902 + ... + 413802098.

It is an arithmetic number, because the mean of its divisors is an integer number (469188720).

Almost surely, 2^81518994000 is an apocalyptic number.

81518994000 is a gapful number since it is divisible by the number (80) 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 81518994000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (150140390400).

81518994000 is an abundant number, since it is smaller than the sum of its proper divisors (218761786800).

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

81518994000 is a wasteful number, since it uses less digits than its factorization.

81518994000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 405 (or 383 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 45.

The spelling of 81518994000 in words is "eighty-one billion, five hundred eighteen million, nine hundred ninety-four thousand".