81109512 has 96 divisors (see below), whose sum is σ = 248582880. Its totient is φ = 24572160.

The previous prime is 81109507. The next prime is 81109517. The reversal of 81109512 is 21590118.

It is an interprime number because it is at equal distance from previous prime (81109507) and next prime (81109517).

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

It is not an unprimeable number, because it can be changed into a prime (81109517) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19488 + ... + 23280.

It is an arithmetic number, because the mean of its divisors is an integer number (2589405).

Almost surely, 2^81109512 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 81109512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (124291440).

81109512 is an abundant number, since it is smaller than the sum of its proper divisors (167473368).

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

81109512 is a wasteful number, since it uses less digits than its factorization.

81109512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3825 (or 3809 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 27.

The square root of 81109512 is about 9006.0819449969. The cubic root of 81109512 is about 432.8697754236.

The spelling of 81109512 in words is "eighty-one million, one hundred nine thousand, five hundred twelve".