687384781 has 2 divisors, whose sum is σ = 687384782. Its totient is φ = 687384780.

The previous prime is 687384769. The next prime is 687384787. The reversal of 687384781 is 187483786.

687384781 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., 524822281 + 162562500 = 22909^2 + 12750^2 .

It is a cyclic number.

It is not a de Polignac number, because 687384781 - 2²³ = 678996173 is a prime.

It is a super-2 number, since 2×687384781² = 944995674300835922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (687384787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343692390 + 343692391.

It is an arithmetic number, because the mean of its divisors is an integer number (343692391).

Almost surely, 2^687384781 is an apocalyptic number.

It is an amenable number.

687384781 is a deficient number, since it is larger than the sum of its proper divisors (1).

687384781 is an equidigital number, since it uses as much as digits as its factorization.

687384781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1806336, while the sum is 52.

The square root of 687384781 is about 26218.0239720693. The cubic root of 687384781 is about 882.5377764460.

The spelling of 687384781 in words is "six hundred eighty-seven million, three hundred eighty-four thousand, seven hundred eighty-one".