81307837309 has 2 divisors, whose sum is σ = 81307837310. Its totient is φ = 81307837308.

The previous prime is 81307837307. The next prime is 81307837333. The reversal of 81307837309 is 90373870318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 78636498084 + 2671339225 = 280422^2 + 51685^2 .

It is a cyclic number.

It is not a de Polignac number, because 81307837309 - 2¹ = 81307837307 is a prime.

It is a super-2 number, since 2×81307837309² (a number of 23 digits) contains 22 as substring.

Together with 81307837307, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81307837307) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40653918654 + 40653918655.

It is an arithmetic number, because the mean of its divisors is an integer number (40653918655).

Almost surely, 2^81307837309 is an apocalyptic number.

It is an amenable number.

81307837309 is a deficient number, since it is larger than the sum of its proper divisors (1).

81307837309 is an equidigital number, since it uses as much as digits as its factorization.

81307837309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 762048, while the sum is 49.

The spelling of 81307837309 in words is "eighty-one billion, three hundred seven million, eight hundred thirty-seven thousand, three hundred nine".