685138398 has 128 divisors (see below), whose sum is σ = 1738782720. Its totient is φ = 175633920.

The previous prime is 685138379. The next prime is 685138417. The reversal of 685138398 is 893831586.

It is an interprime number because it is at equal distance from previous prime (685138379) and next prime (685138417).

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 685138398.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1036188 + ... + 1036848.

It is an arithmetic number, because the mean of its divisors is an integer number (13584240).

Almost surely, 2^685138398 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 685138398, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (869391360).

685138398 is an abundant number, since it is smaller than the sum of its proper divisors (1053644322).

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

685138398 is a wasteful number, since it uses less digits than its factorization.

685138398 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 762.

The product of its digits is 1244160, while the sum is 51.

The square root of 685138398 is about 26175.1484809542. The cubic root of 685138398 is about 881.5753453719.

The spelling of 685138398 in words is "six hundred eighty-five million, one hundred thirty-eight thousand, three hundred ninety-eight".