81595138507 has 2 divisors, whose sum is σ = 81595138508. Its totient is φ = 81595138506.

The previous prime is 81595138477. The next prime is 81595138591. The reversal of 81595138507 is 70583159518.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81595138507 - 2²³ = 81586749899 is a prime.

It is not a weakly prime, because it can be changed into another prime (81595138907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40797569253 + 40797569254.

It is an arithmetic number, because the mean of its divisors is an integer number (40797569254).

Almost surely, 2^81595138507 is an apocalyptic number.

81595138507 is a deficient number, since it is larger than the sum of its proper divisors (1).

81595138507 is an equidigital number, since it uses as much as digits as its factorization.

81595138507 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1512000, while the sum is 52.

It can be divided in two parts, 815951 and 38507, that added together give a palindrome (854458).

The spelling of 81595138507 in words is "eighty-one billion, five hundred ninety-five million, one hundred thirty-eight thousand, five hundred seven".