81107520 has 224 divisors, whose sum is σ = 284366208. Its totient is φ = 19464192.

The previous prime is 81107513. The next prime is 81107531. The reversal of 81107520 is 2570118.

It is a Harshad number since it is a multiple of its sum of digits (24).

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 31 ways as a sum of consecutive naturals, for example, 836112 + ... + 836208.

It is an arithmetic number, because the mean of its divisors is an integer number (1269492).

Almost surely, 2^81107520 is an apocalyptic number.

81107520 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 81107520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (142183104).

81107520 is an abundant number, since it is smaller than the sum of its proper divisors (203258688).

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

81107520 is a wasteful number, since it uses less digits than its factorization.

81107520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 197 (or 187 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 24.

The square root of 81107520 is about 9005.9713523861. The cubic root of 81107520 is about 432.8662317223.

Adding to 81107520 its reverse (2570118), we get a palindrome (83677638).

The spelling of 81107520 in words is "eighty-one million, one hundred seven thousand, five hundred twenty".