688721461 has 2 divisors, whose sum is σ = 688721462. Its totient is φ = 688721460.

The previous prime is 688721399. The next prime is 688721521. The reversal of 688721461 is 164127886.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 688065361 + 656100 = 26231^2 + 810^2 .

It is a cyclic number.

It is not a de Polignac number, because 688721461 - 2⁷ = 688721333 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (688727461) 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, 344360730 + 344360731.

It is an arithmetic number, because the mean of its divisors is an integer number (344360731).

Almost surely, 2^688721461 is an apocalyptic number.

It is an amenable number.

688721461 is a deficient number, since it is larger than the sum of its proper divisors (1).

688721461 is an equidigital number, since it uses as much as digits as its factorization.

688721461 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 129024, while the sum is 43.

The square root of 688721461 is about 26243.5032150816. The cubic root of 688721461 is about 883.1094634133.

The spelling of 688721461 in words is "six hundred eighty-eight million, seven hundred twenty-one thousand, four hundred sixty-one".