685129091 has 2 divisors, whose sum is σ = 685129092. Its totient is φ = 685129090.

The previous prime is 685129051. The next prime is 685129097. The reversal of 685129091 is 190921586.

It is a happy number.

685129091 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-685129091 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (685129097) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342564545 + 342564546.

It is an arithmetic number, because the mean of its divisors is an integer number (342564546).

Almost surely, 2^685129091 is an apocalyptic number.

685129091 is a deficient number, since it is larger than the sum of its proper divisors (1).

685129091 is an equidigital number, since it uses as much as digits as its factorization.

685129091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 38880, while the sum is 41.

The square root of 685129091 is about 26174.9706972138. The cubic root of 685129091 is about 881.5713535464.

The spelling of 685129091 in words is "six hundred eighty-five million, one hundred twenty-nine thousand, ninety-one".