781636312913 has 4 divisors (see below), whose sum is σ = 781703125428. Its totient is φ = 781569500400.

The previous prime is 781636312907. The next prime is 781636312921. The reversal of 781636312913 is 319213636187.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 319213636187 = 59621 ⋅5354047.

It can be written as a sum of positive squares in 2 ways, for example, as 672519725329 + 109116587584 = 820073^2 + 330328^2 .

It is a cyclic number.

It is not a de Polignac number, because 781636312913 - 2¹⁰ = 781636311889 is a prime.

It is a super-2 number, since 2×781636312913² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (781636312973) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33388706 + ... + 33412107.

It is an arithmetic number, because the mean of its divisors is an integer number (195425781357).

Almost surely, 2^781636312913 is an apocalyptic number.

It is an amenable number.

781636312913 is a deficient number, since it is larger than the sum of its proper divisors (66812515).

781636312913 is a wasteful number, since it uses less digits than its factorization.

781636312913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66812514.

The product of its digits is 979776, while the sum is 50.

The spelling of 781636312913 in words is "seven hundred eighty-one billion, six hundred thirty-six million, three hundred twelve thousand, nine hundred thirteen".