81173697 has 32 divisors (see below), whose sum is σ = 123327360. Its totient is φ = 47432000.

The previous prime is 81173689. The next prime is 81173699. The reversal of 81173697 is 79637118.

It is not a de Polignac number, because 81173697 - 2³ = 81173689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81173699) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 115447 + ... + 116147.

It is an arithmetic number, because the mean of its divisors is an integer number (3853980).

Almost surely, 2^81173697 is an apocalyptic number.

81173697 is a gapful number since it is divisible by the number (87) formed by its first and last digit.

It is an amenable number.

81173697 is a deficient number, since it is larger than the sum of its proper divisors (42153663).

81173697 is a wasteful number, since it uses less digits than its factorization.

81173697 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 766 (or 744 counting only the distinct ones).

The product of its digits is 63504, while the sum is 42.

The square root of 81173697 is about 9009.6446655792. The cubic root of 81173697 is about 432.9839273494.

The spelling of 81173697 in words is "eighty-one million, one hundred seventy-three thousand, six hundred ninety-seven".