81817929 has 12 divisors (see below), whose sum is σ = 120696576. Its totient is φ = 53384472.

The previous prime is 81817913. The next prime is 81817943. The reversal of 81817929 is 92971818.

It is not a de Polignac number, because 81817929 - 2⁴ = 81817913 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81817999) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 96289 + ... + 97134.

It is an arithmetic number, because the mean of its divisors is an integer number (10058048).

Almost surely, 2^81817929 is an apocalyptic number.

It is an amenable number.

81817929 is a deficient number, since it is larger than the sum of its proper divisors (38878647).

81817929 is a wasteful number, since it uses less digits than its factorization.

81817929 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193476 (or 193473 counting only the distinct ones).

The product of its digits is 72576, while the sum is 45.

The square root of 81817929 is about 9045.3263622713. The cubic root of 81817929 is about 434.1263639205.

It can be divided in two parts, 8181 and 7929, that added together give a triangular number (16110 = T₁₇₉).

The spelling of 81817929 in words is "eighty-one million, eight hundred seventeen thousand, nine hundred twenty-nine".