684138388 has 12 divisors (see below), whose sum is σ = 1198474452. Its totient is φ = 341717120.

The previous prime is 684138383. The next prime is 684138421. The reversal of 684138388 is 883831486.

684138388 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 288048784 + 396089604 = 16972^2 + 19902^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (684138383) 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, 83623 + ... + 91438.

It is an arithmetic number, because the mean of its divisors is an integer number (99872871).

Almost surely, 2^684138388 is an apocalyptic number.

It is an amenable number.

684138388 is a deficient number, since it is larger than the sum of its proper divisors (514336064).

684138388 is a wasteful number, since it uses less digits than its factorization.

684138388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 176042 (or 176040 counting only the distinct ones).

The product of its digits is 884736, while the sum is 49.

The square root of 684138388 is about 26156.0392261520. The cubic root of 684138388 is about 881.1462284596.

The spelling of 684138388 in words is "six hundred eighty-four million, one hundred thirty-eight thousand, three hundred eighty-eight".