81306073 has 4 divisors (see below), whose sum is σ = 85585360. Its totient is φ = 77026788.

The previous prime is 81306059. The next prime is 81306083. The reversal of 81306073 is 37060318.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81306073 - 2¹⁷ = 81175001 is a prime.

It is a super-2 number, since 2×81306073² = 13221355013362658, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81306083) 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 3 ways as a sum of consecutive naturals, for example, 2139615 + ... + 2139652.

It is an arithmetic number, because the mean of its divisors is an integer number (21396340).

Almost surely, 2^81306073 is an apocalyptic number.

It is an amenable number.

81306073 is a deficient number, since it is larger than the sum of its proper divisors (4279287).

81306073 is a wasteful number, since it uses less digits than its factorization.

81306073 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4279286.

The product of its (nonzero) digits is 3024, while the sum is 28.

The square root of 81306073 is about 9016.9880226160. The cubic root of 81306073 is about 433.2191659132.

The spelling of 81306073 in words is "eighty-one million, three hundred six thousand, seventy-three".