81755812 has 24 divisors (see below), whose sum is σ = 145895904. Its totient is φ = 40077312.

The previous prime is 81755809. The next prime is 81755813. The reversal of 81755812 is 21855718.

It is not an unprimeable number, because it can be changed into a prime (81755813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 68283 + ... + 69469.

It is an arithmetic number, because the mean of its divisors is an integer number (6078996).

Almost surely, 2^81755812 is an apocalyptic number.

It is an amenable number.

81755812 is a deficient number, since it is larger than the sum of its proper divisors (64140092).

81755812 is a wasteful number, since it uses less digits than its factorization.

81755812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1515 (or 1513 counting only the distinct ones).

The product of its digits is 22400, while the sum is 37.

The square root of 81755812 is about 9041.8920586346. The cubic root of 81755812 is about 434.0164717286.

The spelling of 81755812 in words is "eighty-one million, seven hundred fifty-five thousand, eight hundred twelve".