688735891 has 2 divisors, whose sum is σ = 688735892. Its totient is φ = 688735890.

The previous prime is 688735849. The next prime is 688735907. The reversal of 688735891 is 198537886.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 688735891 - 2¹⁵ = 688703123 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (688735991) 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, 344367945 + 344367946.

It is an arithmetic number, because the mean of its divisors is an integer number (344367946).

Almost surely, 2^688735891 is an apocalyptic number.

688735891 is a deficient number, since it is larger than the sum of its proper divisors (1).

688735891 is an equidigital number, since it uses as much as digits as its factorization.

688735891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2903040, while the sum is 55.

The square root of 688735891 is about 26243.7781388275. The cubic root of 688735891 is about 883.1156309674.

It can be divided in two parts, 6887 and 35891, that added together give a triangular number (42778 = T₂₉₂).

The spelling of 688735891 in words is "six hundred eighty-eight million, seven hundred thirty-five thousand, eight hundred ninety-one".