688507138 has 8 divisors (see below), whose sum is σ = 1126648080. Its totient is φ = 312957780.

The previous prime is 688507133. The next prime is 688507147. The reversal of 688507138 is 831705886.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (688507133) 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, 15647868 + ... + 15647911.

It is an arithmetic number, because the mean of its divisors is an integer number (140831010).

Almost surely, 2^688507138 is an apocalyptic number.

688507138 is a deficient number, since it is larger than the sum of its proper divisors (438140942).

688507138 is a wasteful number, since it uses less digits than its factorization.

688507138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31295792.

The product of its (nonzero) digits is 322560, while the sum is 46.

The square root of 688507138 is about 26239.4195438847. The cubic root of 688507138 is about 883.0178490638.

The spelling of 688507138 in words is "six hundred eighty-eight million, five hundred seven thousand, one hundred thirty-eight".