688423805 has 24 divisors (see below), whose sum is σ = 851575128. Its totient is φ = 534238848.

The previous prime is 688423759. The next prime is 688423843. The reversal of 688423805 is 508324886.

It can be written as a sum of positive squares in 4 ways, for example, as 60871204 + 627552601 = 7802^2 + 25051^2 .

It is a de Polignac number, because none of the positive numbers 2^k-688423805 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1733867 + ... + 1734263.

It is an arithmetic number, because the mean of its divisors is an integer number (35482297).

Almost surely, 2^688423805 is an apocalyptic number.

It is an amenable number.

688423805 is a deficient number, since it is larger than the sum of its proper divisors (163151323).

688423805 is a wasteful number, since it uses less digits than its factorization.

688423805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 653 (or 606 counting only the distinct ones).

The product of its (nonzero) digits is 368640, while the sum is 44.

The square root of 688423805 is about 26237.8315605539. The cubic root of 688423805 is about 882.9822224685.

The spelling of 688423805 in words is "six hundred eighty-eight million, four hundred twenty-three thousand, eight hundred five".