686651605 has 4 divisors (see below), whose sum is σ = 823981932. Its totient is φ = 549321280.

The previous prime is 686651569. The next prime is 686651629. The reversal of 686651605 is 506156686.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 77845329 + 608806276 = 8823^2 + 24674^2 .

It is not a de Polignac number, because 686651605 - 2¹⁹ = 686127317 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 68665156 + ... + 68665165.

It is an arithmetic number, because the mean of its divisors is an integer number (205995483).

Almost surely, 2^686651605 is an apocalyptic number.

It is an amenable number.

686651605 is a deficient number, since it is larger than the sum of its proper divisors (137330327).

686651605 is a wasteful number, since it uses less digits than its factorization.

686651605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137330326.

The product of its (nonzero) digits is 259200, while the sum is 43.

The square root of 686651605 is about 26204.0379521936. The cubic root of 686651605 is about 882.2238883470.

The spelling of 686651605 in words is "six hundred eighty-six million, six hundred fifty-one thousand, six hundred five".