81810067 has 4 divisors (see below), whose sum is σ = 86115880. Its totient is φ = 77504256.

The previous prime is 81810041. The next prime is 81810083. The reversal of 81810067 is 76001818.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81810067 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81810007) 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 3 ways as a sum of consecutive naturals, for example, 2152878 + ... + 2152915.

It is an arithmetic number, because the mean of its divisors is an integer number (21528970).

Almost surely, 2^81810067 is an apocalyptic number.

81810067 is a deficient number, since it is larger than the sum of its proper divisors (4305813).

81810067 is a wasteful number, since it uses less digits than its factorization.

81810067 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4305812.

The product of its (nonzero) digits is 2688, while the sum is 31.

The square root of 81810067 is about 9044.8917627576. The cubic root of 81810067 is about 434.1124582039.

The spelling of 81810067 in words is "eighty-one million, eight hundred ten thousand, sixty-seven".