688051561 has 2 divisors, whose sum is σ = 688051562. Its totient is φ = 688051560.

The previous prime is 688051549. The next prime is 688051577. The reversal of 688051561 is 165150886.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 500909161 + 187142400 = 22381^2 + 13680^2 .

It is a cyclic number.

It is not a de Polignac number, because 688051561 - 2¹¹ = 688049513 is a prime.

It is not a weakly prime, because it can be changed into another prime (688051501) 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, 344025780 + 344025781.

It is an arithmetic number, because the mean of its divisors is an integer number (344025781).

Almost surely, 2^688051561 is an apocalyptic number.

It is an amenable number.

688051561 is a deficient number, since it is larger than the sum of its proper divisors (1).

688051561 is an equidigital number, since it uses as much as digits as its factorization.

688051561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 57600, while the sum is 40.

The square root of 688051561 is about 26230.7369511419. The cubic root of 688051561 is about 882.8230452815.

The spelling of 688051561 in words is "six hundred eighty-eight million, fifty-one thousand, five hundred sixty-one".