331221691 has 2 divisors, whose sum is σ = 331221692. Its totient is φ = 331221690.

The previous prime is 331221637. The next prime is 331221713. The reversal of 331221691 is 196122133.

It is a strong prime.

It is an emirp because it is prime and its reverse (196122133) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 331221691 - 2⁹ = 331221179 is a prime.

It is not a weakly prime, because it can be changed into another prime (331221601) 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, 165610845 + 165610846.

It is an arithmetic number, because the mean of its divisors is an integer number (165610846).

Almost surely, 2^331221691 is an apocalyptic number.

331221691 is a deficient number, since it is larger than the sum of its proper divisors (1).

331221691 is an equidigital number, since it uses as much as digits as its factorization.

331221691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1944, while the sum is 28.

The square root of 331221691 is about 18199.4969985437. The cubic root of 331221691 is about 691.8940406832.

The spelling of 331221691 in words is "three hundred thirty-one million, two hundred twenty-one thousand, six hundred ninety-one".