691973 has 2 divisors, whose sum is σ = 691974. Its totient is φ = 691972.

The previous prime is 691949. The next prime is 691979. The reversal of 691973 is 379196.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 588289 + 103684 = 767^2 + 322^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-691973 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 691973.

It is not a weakly prime, because it can be changed into another prime (691979) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345986 + 345987.

It is an arithmetic number, because the mean of its divisors is an integer number (345987).

2⁶⁹¹⁹⁷³ is an apocalyptic number.

It is an amenable number.

691973 is a deficient number, since it is larger than the sum of its proper divisors (1).

691973 is an equidigital number, since it uses as much as digits as its factorization.

691973 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10206, while the sum is 35.

The square root of 691973 is about 831.8491449776. The cubic root of 691973 is about 88.4497038310.

The spelling of 691973 in words is "six hundred ninety-one thousand, nine hundred seventy-three".