320355991 has 2 divisors, whose sum is σ = 320355992. Its totient is φ = 320355990.

The previous prime is 320355961. The next prime is 320356019. The reversal of 320355991 is 199553023.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 320355991 - 2¹³ = 320347799 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 320355991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (320355911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160177995 + 160177996.

It is an arithmetic number, because the mean of its divisors is an integer number (160177996).

Almost surely, 2^320355991 is an apocalyptic number.

320355991 is a deficient number, since it is larger than the sum of its proper divisors (1).

320355991 is an equidigital number, since it uses as much as digits as its factorization.

320355991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36450, while the sum is 37.

The square root of 320355991 is about 17898.4913051352. The cubic root of 320355991 is about 684.2439246927.

It can be divided in two parts, 32035599 and 1, that added together give a square (32035600 = 5660²).

The spelling of 320355991 in words is "three hundred twenty million, three hundred fifty-five thousand, nine hundred ninety-one".