81159756 has 12 divisors (see below), whose sum is σ = 189372792. Its totient is φ = 27053248.

The previous prime is 81159703. The next prime is 81159761. The reversal of 81159756 is 65795118.

It is a tau number, because it is divible by the number of its divisors (12).

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 3381645 + ... + 3381668.

It is an arithmetic number, because the mean of its divisors is an integer number (15781066).

Almost surely, 2^81159756 is an apocalyptic number.

It is an amenable number.

81159756 is an abundant number, since it is smaller than the sum of its proper divisors (108213036).

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

81159756 is a wasteful number, since it uses less digits than its factorization.

81159756 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6763320 (or 6763318 counting only the distinct ones).

The product of its digits is 75600, while the sum is 42.

The square root of 81159756 is about 9008.8709614468. The cubic root of 81159756 is about 432.9591386360.

It can be divided in two parts, 8115 and 9756, that added together give a palindrome (17871).

The spelling of 81159756 in words is "eighty-one million, one hundred fifty-nine thousand, seven hundred fifty-six".