81105540 has 48 divisors (see below), whose sum is σ = 228516288. Its totient is φ = 21492864.

The previous prime is 81105523. The next prime is 81105559. The reversal of 81105540 is 4550118.

It is a self number, because there is not a number n which added to its sum of digits gives 81105540.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 5634 + ... + 13926.

It is an arithmetic number, because the mean of its divisors is an integer number (4760756).

Almost surely, 2^81105540 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 81105540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (114258144).

81105540 is an abundant number, since it is smaller than the sum of its proper divisors (147410748).

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

81105540 is a wasteful number, since it uses less digits than its factorization.

81105540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8468 (or 8466 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 24.

The square root of 81105540 is about 9005.8614246501. The cubic root of 81105540 is about 432.8627093111.

Adding to 81105540 its reverse (4550118), we get a palindrome (85655658).

The spelling of 81105540 in words is "eighty-one million, one hundred five thousand, five hundred forty".