685609638 has 16 divisors (see below), whose sum is σ = 1567107840. Its totient is φ = 195888456.

The previous prime is 685609621. The next prime is 685609663. The reversal of 685609638 is 836906586.

685609638 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8161978 + ... + 8162061.

It is an arithmetic number, because the mean of its divisors is an integer number (97944240).

Almost surely, 2^685609638 is an apocalyptic number.

685609638 is an abundant number, since it is smaller than the sum of its proper divisors (881498202).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

685609638 is a wasteful number, since it uses less digits than its factorization.

685609638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16324051.

The product of its (nonzero) digits is 1866240, while the sum is 51.

The square root of 685609638 is about 26184.1486017781. The cubic root of 685609638 is about 881.7774156679. Note that the first 3 decimals are identical.

The spelling of 685609638 in words is "six hundred eighty-five million, six hundred nine thousand, six hundred thirty-eight".