781449986869 has 2 divisors, whose sum is σ = 781449986870. Its totient is φ = 781449986868.

The previous prime is 781449986803. The next prime is 781449986921. The reversal of 781449986869 is 968689944187.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 484492563025 + 296957423844 = 696055^2 + 544938^2 .

It is a cyclic number.

It is not a de Polignac number, because 781449986869 - 2²⁵ = 781416432437 is a prime.

It is a super-2 number, since 2×781449986869² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (781449986969) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390724993434 + 390724993435.

It is an arithmetic number, because the mean of its divisors is an integer number (390724993435).

Almost surely, 2^781449986869 is an apocalyptic number.

It is an amenable number.

781449986869 is a deficient number, since it is larger than the sum of its proper divisors (1).

781449986869 is an equidigital number, since it uses as much as digits as its factorization.

781449986869 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1504935936, while the sum is 79.

The spelling of 781449986869 in words is "seven hundred eighty-one billion, four hundred forty-nine million, nine hundred eighty-six thousand, eight hundred sixty-nine".