81994000 has 80 divisors (see below), whose sum is σ = 216343296. Its totient is φ = 29808000.

The previous prime is 81993983. The next prime is 81994001. The reversal of 81994000 is 49918.

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (81994001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20137 + ... + 23863.

Almost surely, 2^81994000 is an apocalyptic number.

81994000 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 81994000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (108171648).

81994000 is an abundant number, since it is smaller than the sum of its proper divisors (134349296).

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

81994000 is a wasteful number, since it uses less digits than its factorization.

81994000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3761 (or 3745 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 81994000 is about 9055.0538374987. The cubic root of 81994000 is about 434.4375520221.

The spelling of 81994000 in words is "eighty-one million, nine hundred ninety-four thousand".