688263138 has 12 divisors (see below), whose sum is σ = 1491236838. Its totient is φ = 229421040.

The previous prime is 688263133. The next prime is 688263151. The reversal of 688263138 is 831362886.

688263138 is a `hidden beast` number, since 6 + 8 + 8 + 2 + 631 + 3 + 8 = 666.

It can be written as a sum of positive squares in only one way, i.e., 572979969 + 115283169 = 23937^2 + 10737^2 .

It is a super-2 number, since 2×688263138² = 947412294259214088, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 688263093 and 688263102.

It is not an unprimeable number, because it can be changed into a prime (688263133) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 19118403 + ... + 19118438.

Almost surely, 2^688263138 is an apocalyptic number.

688263138 is an abundant number, since it is smaller than the sum of its proper divisors (802973700).

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

688263138 is a wasteful number, since it uses less digits than its factorization.

688263138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38236849 (or 38236846 counting only the distinct ones).

The product of its digits is 331776, while the sum is 45.

The square root of 688263138 is about 26234.7696387828. The cubic root of 688263138 is about 882.9135258597.

The spelling of 688263138 in words is "six hundred eighty-eight million, two hundred sixty-three thousand, one hundred thirty-eight".