81307800 has 288 divisors, whose sum is σ = 324979200. Its totient is φ = 18506880.

The previous prime is 81307789. The next prime is 81307801. The reversal of 81307800 is 870318.

It is a super-2 number, since 2×81307800² = 13221916681680000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81307801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 340081 + ... + 340319.

It is an arithmetic number, because the mean of its divisors is an integer number (1128400).

Almost surely, 2^81307800 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81307800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (162489600).

81307800 is an abundant number, since it is smaller than the sum of its proper divisors (243671400).

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

81307800 is a wasteful number, since it uses less digits than its factorization.

81307800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 277 (or 256 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 27.

The square root of 81307800 is about 9017.0837857924. The cubic root of 81307800 is about 433.2222331880. Note that the first 4 decimals are identical.

The spelling of 81307800 in words is "eighty-one million, three hundred seven thousand, eight hundred".