691216373 has 2 divisors, whose sum is σ = 691216374. Its totient is φ = 691216372.

The previous prime is 691216349. The next prime is 691216381. The reversal of 691216373 is 373612196.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 433389124 + 257827249 = 20818^2 + 16057^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-691216373 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691216313) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345608186 + 345608187.

It is an arithmetic number, because the mean of its divisors is an integer number (345608187).

Almost surely, 2^691216373 is an apocalyptic number.

It is an amenable number.

691216373 is a deficient number, since it is larger than the sum of its proper divisors (1).

691216373 is an equidigital number, since it uses as much as digits as its factorization.

691216373 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40824, while the sum is 38.

The square root of 691216373 is about 26290.9941424816. The cubic root of 691216373 is about 884.1745409435.

The spelling of 691216373 in words is "six hundred ninety-one million, two hundred sixteen thousand, three hundred seventy-three".