685009639 has 4 divisors (see below), whose sum is σ = 686509024. Its totient is φ = 683510256.

The previous prime is 685009627. The next prime is 685009649. The reversal of 685009639 is 936900586.

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

It is a cyclic number.

It is not a de Polignac number, because 685009639 - 2²¹ = 682912487 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (685009649) 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, 749007 + ... + 749920.

It is an arithmetic number, because the mean of its divisors is an integer number (171627256).

Almost surely, 2^685009639 is an apocalyptic number.

685009639 is a deficient number, since it is larger than the sum of its proper divisors (1499385).

685009639 is a wasteful number, since it uses less digits than its factorization.

685009639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1499384.

The product of its (nonzero) digits is 349920, while the sum is 46.

The square root of 685009639 is about 26172.6887995865. The cubic root of 685009639 is about 881.5201166903.

The spelling of 685009639 in words is "six hundred eighty-five million, nine thousand, six hundred thirty-nine".