691680673 has 2 divisors, whose sum is σ = 691680674. Its totient is φ = 691680672.

The previous prime is 691680667. The next prime is 691680697. The reversal of 691680673 is 376086196.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 686073249 + 5607424 = 26193^2 + 2368^2 .

It is a cyclic number.

It is not a de Polignac number, because 691680673 - 2⁵ = 691680641 is a prime.

It is not a weakly prime, because it can be changed into another prime (691680643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345840336 + 345840337.

It is an arithmetic number, because the mean of its divisors is an integer number (345840337).

Almost surely, 2^691680673 is an apocalyptic number.

It is an amenable number.

691680673 is a deficient number, since it is larger than the sum of its proper divisors (1).

691680673 is an equidigital number, since it uses as much as digits as its factorization.

691680673 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 326592, while the sum is 46.

The square root of 691680673 is about 26299.8226800106. The cubic root of 691680673 is about 884.3724675609.

The spelling of 691680673 in words is "six hundred ninety-one million, six hundred eighty thousand, six hundred seventy-three".