686066209 has 4 divisors (see below), whose sum is σ = 686133504. Its totient is φ = 685998916.

The previous prime is 686066203. The next prime is 686066221. The reversal of 686066209 is 902660686.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 902660686 = 2 ⋅451330343.

It is a cyclic number.

It is not a de Polignac number, because 686066209 - 2²³ = 677677601 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (686066203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14857 + ... + 39910.

It is an arithmetic number, because the mean of its divisors is an integer number (171533376).

Almost surely, 2^686066209 is an apocalyptic number.

It is an amenable number.

686066209 is a deficient number, since it is larger than the sum of its proper divisors (67295).

686066209 is a wasteful number, since it uses less digits than its factorization.

686066209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67294.

The product of its (nonzero) digits is 186624, while the sum is 43.

The square root of 686066209 is about 26192.8656126053. The cubic root of 686066209 is about 881.9731075214.

The spelling of 686066209 in words is "six hundred eighty-six million, sixty-six thousand, two hundred nine".