81491509339 has 2 divisors, whose sum is σ = 81491509340. Its totient is φ = 81491509338.

The previous prime is 81491509283. The next prime is 81491509361. The reversal of 81491509339 is 93390519418.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81491509339 is a prime.

It is not a weakly prime, because it can be changed into another prime (81491501339) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40745754669 + 40745754670.

It is an arithmetic number, because the mean of its divisors is an integer number (40745754670).

Almost surely, 2^81491509339 is an apocalyptic number.

81491509339 is a deficient number, since it is larger than the sum of its proper divisors (1).

81491509339 is an equidigital number, since it uses as much as digits as its factorization.

81491509339 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1049760, while the sum is 52.

The spelling of 81491509339 in words is "eighty-one billion, four hundred ninety-one million, five hundred nine thousand, three hundred thirty-nine".