686463781 has 2 divisors, whose sum is σ = 686463782. Its totient is φ = 686463780.

The previous prime is 686463733. The next prime is 686463793. The reversal of 686463781 is 187364686.

686463781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 658743556 + 27720225 = 25666^2 + 5265^2 .

It is a cyclic number.

It is not a de Polignac number, because 686463781 - 2⁹ = 686463269 is a prime.

It is a super-2 number, since 2×686463781² = 942465045249631922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (686463731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343231890 + 343231891.

It is an arithmetic number, because the mean of its divisors is an integer number (343231891).

Almost surely, 2^686463781 is an apocalyptic number.

It is an amenable number.

686463781 is a deficient number, since it is larger than the sum of its proper divisors (1).

686463781 is an equidigital number, since it uses as much as digits as its factorization.

686463781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1161216, while the sum is 49.

The square root of 686463781 is about 26200.4538319473. The cubic root of 686463781 is about 882.1434409851.

It can be divided in two parts, 68646 and 3781, that added together give a palindrome (72427).

The spelling of 686463781 in words is "six hundred eighty-six million, four hundred sixty-three thousand, seven hundred eighty-one".