781128316321 has 2 divisors, whose sum is σ = 781128316322. Its totient is φ = 781128316320.

The previous prime is 781128316277. The next prime is 781128316327. The reversal of 781128316321 is 123613821187.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 768112016400 + 13016299921 = 876420^2 + 114089^2 .

It is a cyclic number.

It is not a de Polignac number, because 781128316321 - 2⁹ = 781128315809 is a prime.

It is a super-2 number, since 2×781128316321² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (781128316327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390564158160 + 390564158161.

It is an arithmetic number, because the mean of its divisors is an integer number (390564158161).

Almost surely, 2^781128316321 is an apocalyptic number.

It is an amenable number.

781128316321 is a deficient number, since it is larger than the sum of its proper divisors (1).

781128316321 is an equidigital number, since it uses as much as digits as its factorization.

781128316321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 96768, while the sum is 43.

The spelling of 781128316321 in words is "seven hundred eighty-one billion, one hundred twenty-eight million, three hundred sixteen thousand, three hundred twenty-one".