688138905 has 8 divisors (see below), whose sum is σ = 1101022272. Its totient is φ = 367007408.

The previous prime is 688138879. The next prime is 688138907. The reversal of 688138905 is 509831886.

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

It is a cyclic number.

It is not a de Polignac number, because 688138905 - 2¹⁰ = 688137881 is a prime.

It is not an unprimeable number, because it can be changed into a prime (688138907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22937949 + ... + 22937978.

It is an arithmetic number, because the mean of its divisors is an integer number (137627784).

Almost surely, 2^688138905 is an apocalyptic number.

It is an amenable number.

688138905 is a deficient number, since it is larger than the sum of its proper divisors (412883367).

688138905 is a wasteful number, since it uses less digits than its factorization.

688138905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45875935.

The product of its (nonzero) digits is 414720, while the sum is 48.

The square root of 688138905 is about 26232.4018153123. The cubic root of 688138905 is about 882.8604000564.

The spelling of 688138905 in words is "six hundred eighty-eight million, one hundred thirty-eight thousand, nine hundred five".