688636609261 has 2 divisors, whose sum is σ = 688636609262. Its totient is φ = 688636609260.

The previous prime is 688636609231. The next prime is 688636609291. The reversal of 688636609261 is 162906636886.

It is a balanced prime because it is at equal distance from previous prime (688636609231) and next prime (688636609291).

It can be written as a sum of positive squares in only one way, i.e., 490161013225 + 198475596036 = 700115^2 + 445506^2 .

It is a cyclic number.

It is not a de Polignac number, because 688636609261 - 2¹⁵ = 688636576493 is a prime.

It is a super-2 number, since 2×688636609261² (a number of 24 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 688636609261.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (688636609231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344318304630 + 344318304631.

It is an arithmetic number, because the mean of its divisors is an integer number (344318304631).

Almost surely, 2^688636609261 is an apocalyptic number.

It is an amenable number.

688636609261 is a deficient number, since it is larger than the sum of its proper divisors (1).

688636609261 is an equidigital number, since it uses as much as digits as its factorization.

688636609261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 26873856, while the sum is 61.

The spelling of 688636609261 in words is "six hundred eighty-eight billion, six hundred thirty-six million, six hundred nine thousand, two hundred sixty-one".