81288900 has 576 divisors, whose sum is σ = 359976960. Its totient is φ = 15206400.

The previous prime is 81288899. The next prime is 81288901. The reversal of 81288900 is 988218.

It is an interprime number because it is at equal distance from previous prime (81288899) and next prime (81288901).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81288901) 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 191 ways as a sum of consecutive naturals, for example, 3534289 + ... + 3534311.

It is an arithmetic number, because the mean of its divisors is an integer number (624960).

Almost surely, 2^81288900 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 81288900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (179988480).

81288900 is an abundant number, since it is smaller than the sum of its proper divisors (278688060).

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

81288900 is a wasteful number, since it uses less digits than its factorization.

81288900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81 (or 68 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 36.

The square root of 81288900 is about 9016.0357142150. The cubic root of 81288900 is about 433.1886630807.

The spelling of 81288900 in words is "eighty-one million, two hundred eighty-eight thousand, nine hundred".