688631057 has 2 divisors, whose sum is σ = 688631058. Its totient is φ = 688631056.

The previous prime is 688631051. The next prime is 688631081. The reversal of 688631057 is 750136886.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 678029521 + 10601536 = 26039^2 + 3256^2 .

It is a cyclic number.

It is not a de Polignac number, because 688631057 - 2¹⁴ = 688614673 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 688630999 and 688631017.

It is not a weakly prime, because it can be changed into another prime (688631051) 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 as a sum of consecutive naturals, namely, 344315528 + 344315529.

It is an arithmetic number, because the mean of its divisors is an integer number (344315529).

Almost surely, 2^688631057 is an apocalyptic number.

It is an amenable number.

688631057 is a deficient number, since it is larger than the sum of its proper divisors (1).

688631057 is an equidigital number, since it uses as much as digits as its factorization.

688631057 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 241920, while the sum is 44.

The square root of 688631057 is about 26241.7807513134. The cubic root of 688631057 is about 883.0708217050.

The spelling of 688631057 in words is "six hundred eighty-eight million, six hundred thirty-one thousand, fifty-seven".