691991266 has 8 divisors (see below), whose sum is σ = 1038149100. Its totient is φ = 345941568.

The previous prime is 691991263. The next prime is 691991291. The reversal of 691991266 is 662199196.

It can be written as a sum of positive squares in 2 ways, for example, as 652036225 + 39955041 = 25535^2 + 6321^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (691991263) 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 in 3 ways as a sum of consecutive naturals, for example, 8491 + ... + 38158.

Almost surely, 2^691991266 is an apocalyptic number.

691991266 is a deficient number, since it is larger than the sum of its proper divisors (346157834).

691991266 is a wasteful number, since it uses less digits than its factorization.

691991266 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54068.

The product of its digits is 314928, while the sum is 49.

The square root of 691991266 is about 26305.7268669771. The cubic root of 691991266 is about 884.5048209260.

The spelling of 691991266 in words is "six hundred ninety-one million, nine hundred ninety-one thousand, two hundred sixty-six".