691133551 has 2 divisors, whose sum is σ = 691133552. Its totient is φ = 691133550.

The previous prime is 691133549. The next prime is 691133587. The reversal of 691133551 is 155331196.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 691133551 - 2¹ = 691133549 is a prime.

Together with 691133549, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691133591) 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, 345566775 + 345566776.

It is an arithmetic number, because the mean of its divisors is an integer number (345566776).

Almost surely, 2^691133551 is an apocalyptic number.

691133551 is a deficient number, since it is larger than the sum of its proper divisors (1).

691133551 is an equidigital number, since it uses as much as digits as its factorization.

691133551 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12150, while the sum is 34.

The square root of 691133551 is about 26289.4189931995. The cubic root of 691133551 is about 884.1392254082.

The spelling of 691133551 in words is "six hundred ninety-one million, one hundred thirty-three thousand, five hundred fifty-one".