685769209 has 4 divisors (see below), whose sum is σ = 687250816. Its totient is φ = 684287604.

The previous prime is 685769179. The next prime is 685769237. The reversal of 685769209 is 902967586.

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.

It is a cyclic number.

It is not a de Polignac number, because 685769209 - 2⁹ = 685768697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (685769009) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 740109 + ... + 741034.

It is an arithmetic number, because the mean of its divisors is an integer number (171812704).

Almost surely, 2^685769209 is an apocalyptic number.

It is an amenable number.

685769209 is a deficient number, since it is larger than the sum of its proper divisors (1481607).

685769209 is a wasteful number, since it uses less digits than its factorization.

685769209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1481606.

The product of its (nonzero) digits is 1632960, while the sum is 52.

The square root of 685769209 is about 26187.1955161296. The cubic root of 685769209 is about 881.8458196019.

The spelling of 685769209 in words is "six hundred eighty-five million, seven hundred sixty-nine thousand, two hundred nine".