81320311 has 2 divisors, whose sum is σ = 81320312. Its totient is φ = 81320310.

The previous prime is 81320303. The next prime is 81320359. The reversal of 81320311 is 11302318.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81320311 - 2³ = 81320303 is a prime.

It is a super-2 number, since 2×81320311² = 13225985962273442, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81330311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40660155 + 40660156.

It is an arithmetic number, because the mean of its divisors is an integer number (40660156).

Almost surely, 2^81320311 is an apocalyptic number.

81320311 is a deficient number, since it is larger than the sum of its proper divisors (1).

81320311 is an equidigital number, since it uses as much as digits as its factorization.

81320311 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 81320311 is about 9017.7774978095. Note that the first 3 decimals coincide. The cubic root of 81320311 is about 433.2444523166.

Adding to 81320311 its reverse (11302318), we get a palindrome (92622629).

The spelling of 81320311 in words is "eighty-one million, three hundred twenty thousand, three hundred eleven".