691543321 has 12 divisors (see below), whose sum is σ = 810789888. Its totient is φ = 588078792.

The previous prime is 691543313. The next prime is 691543343. The reversal of 691543321 is 123345196.

It is not a de Polignac number, because 691543321 - 2³ = 691543313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (691549321) 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 in 11 ways as a sum of consecutive naturals, for example, 49341 + ... + 61786.

It is an arithmetic number, because the mean of its divisors is an integer number (67565824).

Almost surely, 2^691543321 is an apocalyptic number.

It is an amenable number.

691543321 is a deficient number, since it is larger than the sum of its proper divisors (119246567).

691543321 is a wasteful number, since it uses less digits than its factorization.

691543321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111268 (or 111261 counting only the distinct ones).

The product of its digits is 19440, while the sum is 34.

The square root of 691543321 is about 26297.2112780044. The cubic root of 691543321 is about 884.3139249544.

The spelling of 691543321 in words is "six hundred ninety-one million, five hundred forty-three thousand, three hundred twenty-one".