81330857939 has 2 divisors, whose sum is σ = 81330857940. Its totient is φ = 81330857938.

The previous prime is 81330857899. The next prime is 81330857963. The reversal of 81330857939 is 93975803318.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81330857939 - 2³⁶ = 12611381203 is a prime.

It is a super-2 number, since 2×81330857939² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81330857999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40665428969 + 40665428970.

It is an arithmetic number, because the mean of its divisors is an integer number (40665428970).

Almost surely, 2^81330857939 is an apocalyptic number.

81330857939 is a deficient number, since it is larger than the sum of its proper divisors (1).

81330857939 is an equidigital number, since it uses as much as digits as its factorization.

81330857939 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4898880, while the sum is 56.

The spelling of 81330857939 in words is "eighty-one billion, three hundred thirty million, eight hundred fifty-seven thousand, nine hundred thirty-nine".