320403991 has 2 divisors, whose sum is σ = 320403992. Its totient is φ = 320403990.

The previous prime is 320403989. The next prime is 320404001. The reversal of 320403991 is 199304023.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 320403991 - 2¹ = 320403989 is a prime.

Together with 320403989, 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 (320403691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160201995 + 160201996.

It is an arithmetic number, because the mean of its divisors is an integer number (160201996).

Almost surely, 2^320403991 is an apocalyptic number.

320403991 is a deficient number, since it is larger than the sum of its proper divisors (1).

320403991 is an equidigital number, since it uses as much as digits as its factorization.

320403991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5832, while the sum is 31.

The square root of 320403991 is about 17899.8321500510. The cubic root of 320403991 is about 684.2780971644.

The spelling of 320403991 in words is "three hundred twenty million, four hundred three thousand, nine hundred ninety-one".