686851993 has 2 divisors, whose sum is σ = 686851994. Its totient is φ = 686851992.

The previous prime is 686851961. The next prime is 686852011. The reversal of 686851993 is 399158686.

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., 542563849 + 144288144 = 23293^2 + 12012^2 .

It is a cyclic number.

It is not a de Polignac number, because 686851993 - 2⁵ = 686851961 is a prime.

It is not a weakly prime, because it can be changed into another prime (687851993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343425996 + 343425997.

It is an arithmetic number, because the mean of its divisors is an integer number (343425997).

Almost surely, 2^686851993 is an apocalyptic number.

It is an amenable number.

686851993 is a deficient number, since it is larger than the sum of its proper divisors (1).

686851993 is an equidigital number, since it uses as much as digits as its factorization.

686851993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2799360, while the sum is 55.

The square root of 686851993 is about 26207.8612824473. The cubic root of 686851993 is about 882.3097008535.

The spelling of 686851993 in words is "six hundred eighty-six million, eight hundred fifty-one thousand, nine hundred ninety-three".