687419809 has 2 divisors, whose sum is σ = 687419810. Its totient is φ = 687419808.

The previous prime is 687419779. The next prime is 687419813. The reversal of 687419809 is 908914786.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 448253584 + 239166225 = 21172^2 + 15465^2 .

It is a cyclic number.

It is not a de Polignac number, because 687419809 - 2¹¹ = 687417761 is a prime.

It is not a weakly prime, because it can be changed into another prime (687419819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343709904 + 343709905.

It is an arithmetic number, because the mean of its divisors is an integer number (343709905).

Almost surely, 2^687419809 is an apocalyptic number.

It is an amenable number.

687419809 is a deficient number, since it is larger than the sum of its proper divisors (1).

687419809 is an equidigital number, since it uses as much as digits as its factorization.

687419809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 870912, while the sum is 52.

The square root of 687419809 is about 26218.6919772898. The cubic root of 687419809 is about 882.5527670835.

The spelling of 687419809 in words is "six hundred eighty-seven million, four hundred nineteen thousand, eight hundred nine".