781709780009 has 2 divisors, whose sum is σ = 781709780010. Its totient is φ = 781709780008.

The previous prime is 781709779973. The next prime is 781709780039. The reversal of 781709780009 is 900087907187.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 570319488025 + 211390291984 = 755195^2 + 459772^2 .

It is a cyclic number.

It is not a de Polignac number, because 781709780009 - 2²⁸ = 781441344553 is a prime.

It is a super-2 number, since 2×781709780009² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (781709780039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390854890004 + 390854890005.

It is an arithmetic number, because the mean of its divisors is an integer number (390854890005).

Almost surely, 2^781709780009 is an apocalyptic number.

It is an amenable number.

781709780009 is a deficient number, since it is larger than the sum of its proper divisors (1).

781709780009 is an equidigital number, since it uses as much as digits as its factorization.

781709780009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1778112, while the sum is 56.

The spelling of 781709780009 in words is "seven hundred eighty-one billion, seven hundred nine million, seven hundred eighty thousand, nine".