691861139 has 2 divisors, whose sum is σ = 691861140. Its totient is φ = 691861138.

The previous prime is 691861073. The next prime is 691861151. The reversal of 691861139 is 931168196.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-691861139 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 691861139.

It is not a weakly prime, because it can be changed into another prime (691864139) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345930569 + 345930570.

It is an arithmetic number, because the mean of its divisors is an integer number (345930570).

Almost surely, 2^691861139 is an apocalyptic number.

691861139 is a deficient number, since it is larger than the sum of its proper divisors (1).

691861139 is an equidigital number, since it uses as much as digits as its factorization.

691861139 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 69984, while the sum is 44.

The square root of 691861139 is about 26303.2533919285. The cubic root of 691861139 is about 884.4493745739.

The spelling of 691861139 in words is "six hundred ninety-one million, eight hundred sixty-one thousand, one hundred thirty-nine".