691348261 has 2 divisors, whose sum is σ = 691348262. Its totient is φ = 691348260.

The previous prime is 691348243. The next prime is 691348279. The reversal of 691348261 is 162843196.

It is a balanced prime because it is at equal distance from previous prime (691348243) and next prime (691348279).

It can be written as a sum of positive squares in only one way, i.e., 505980036 + 185368225 = 22494^2 + 13615^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-691348261 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691348241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345674130 + 345674131.

It is an arithmetic number, because the mean of its divisors is an integer number (345674131).

Almost surely, 2^691348261 is an apocalyptic number.

It is an amenable number.

691348261 is a deficient number, since it is larger than the sum of its proper divisors (1).

691348261 is an equidigital number, since it uses as much as digits as its factorization.

691348261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 62208, while the sum is 40.

The square root of 691348261 is about 26293.5022581626. The cubic root of 691348261 is about 884.2307725378.

The spelling of 691348261 in words is "six hundred ninety-one million, three hundred forty-eight thousand, two hundred sixty-one".