81840000 has 320 divisors, whose sum is σ = 305902080. Its totient is φ = 19200000.

The previous prime is 81839987. The next prime is 81840007. The reversal of 81840000 is 4818.

It is a tau number, because it is divible by the number of its divisors (320).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81840007) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 2639985 + ... + 2640015.

It is an arithmetic number, because the mean of its divisors is an integer number (955944).

Almost surely, 2^81840000 is an apocalyptic number.

81840000 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 81840000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (152951040).

81840000 is an abundant number, since it is smaller than the sum of its proper divisors (224062080).

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

81840000 is a wasteful number, since it uses less digits than its factorization.

81840000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79 (or 52 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 21.

The square root of 81840000 is about 9046.5463023189. The cubic root of 81840000 is about 434.1653966919.

Adding to 81840000 its reverse (4818), we get a palindrome (81844818).

The spelling of 81840000 in words is "eighty-one million, eight hundred forty thousand".