781931149409 has 4 divisors (see below), whose sum is σ = 801002640900. Its totient is φ = 762859657920.

The previous prime is 781931149369. The next prime is 781931149421. The reversal of 781931149409 is 904941139187.

781931149409 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 279856870225 + 502074279184 = 529015^2 + 708572^2 .

It is a de Polignac number, because none of the positive numbers 2^k-781931149409 is a prime.

It is a super-2 number, since 2×781931149409² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (781931149499) 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, 9535745684 + ... + 9535745765.

It is an arithmetic number, because the mean of its divisors is an integer number (200250660225).

Almost surely, 2^781931149409 is an apocalyptic number.

It is an amenable number.

781931149409 is a deficient number, since it is larger than the sum of its proper divisors (19071491491).

781931149409 is a wasteful number, since it uses less digits than its factorization.

781931149409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19071491490.

The product of its (nonzero) digits is 1959552, while the sum is 56.

The spelling of 781931149409 in words is "seven hundred eighty-one billion, nine hundred thirty-one million, one hundred forty-nine thousand, four hundred nine".