691438757 has 2 divisors, whose sum is σ = 691438758. Its totient is φ = 691438756.

The previous prime is 691438733. The next prime is 691438763. The reversal of 691438757 is 757834196.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 663886756 + 27552001 = 25766^2 + 5249^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-691438757 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691438777) 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, 345719378 + 345719379.

It is an arithmetic number, because the mean of its divisors is an integer number (345719379).

Almost surely, 2^691438757 is an apocalyptic number.

It is an amenable number.

691438757 is a deficient number, since it is larger than the sum of its proper divisors (1).

691438757 is an equidigital number, since it uses as much as digits as its factorization.

691438757 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1270080, while the sum is 50.

The square root of 691438757 is about 26295.2230832902. The cubic root of 691438757 is about 884.2693521564.

The spelling of 691438757 in words is "six hundred ninety-one million, four hundred thirty-eight thousand, seven hundred fifty-seven".