781247319991 has 2 divisors, whose sum is σ = 781247319992. Its totient is φ = 781247319990.

The previous prime is 781247319989. The next prime is 781247320031. The reversal of 781247319991 is 199913742187.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 781247319991 - 2¹ = 781247319989 is a prime.

It is a super-2 number, since 2×781247319991² (a number of 25 digits) contains 22 as substring.

Together with 781247319989, 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 (781247319971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390623659995 + 390623659996.

It is an arithmetic number, because the mean of its divisors is an integer number (390623659996).

Almost surely, 2^781247319991 is an apocalyptic number.

781247319991 is a deficient number, since it is larger than the sum of its proper divisors (1).

781247319991 is an equidigital number, since it uses as much as digits as its factorization.

781247319991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6858432, while the sum is 61.

The spelling of 781247319991 in words is "seven hundred eighty-one billion, two hundred forty-seven million, three hundred nineteen thousand, nine hundred ninety-one".