81306311 has 4 divisors (see below), whose sum is σ = 84841392. Its totient is φ = 77771232.

The previous prime is 81306299. The next prime is 81306317. The reversal of 81306311 is 11360318.

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

It is a cyclic number.

It is not a de Polignac number, because 81306311 - 2¹⁴ = 81289927 is a prime.

It is a super-2 number, since 2×81306311² = 13221432416857442, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (23), and also a Moran number because the ratio is a prime number: 3535057 = 81306311 / (8 + 1 + 3 + 0 + 6 + 3 + 1 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81306317) 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, 1767506 + ... + 1767551.

It is an arithmetic number, because the mean of its divisors is an integer number (21210348).

Almost surely, 2^81306311 is an apocalyptic number.

81306311 is a deficient number, since it is larger than the sum of its proper divisors (3535081).

81306311 is a wasteful number, since it uses less digits than its factorization.

81306311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3535080.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 81306311 is about 9017.0012199179. The cubic root of 81306311 is about 433.2195886207.

Adding to 81306311 its reverse (11360318), we get a palindrome (92666629).

It can be divided in two parts, 8130 and 6311, that added together give a palindrome (14441).

The spelling of 81306311 in words is "eighty-one million, three hundred six thousand, three hundred eleven".