1991442331 has 2 divisors, whose sum is σ = 1991442332. Its totient is φ = 1991442330.

The previous prime is 1991442319. The next prime is 1991442347. The reversal of 1991442331 is 1332441991.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (1332441991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1991442331 - 2⁹ = 1991441819 is a prime.

It is a super-2 number, since 2×1991442331² = 7931685115397427122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1991442031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995721165 + 995721166.

It is an arithmetic number, because the mean of its divisors is an integer number (995721166).

Almost surely, 2^1991442331 is an apocalyptic number.

1991442331 is a deficient number, since it is larger than the sum of its proper divisors (1).

1991442331 is an equidigital number, since it uses as much as digits as its factorization.

1991442331 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23328, while the sum is 37.

The square root of 1991442331 is about 44625.5793351750. The cubic root of 1991442331 is about 1258.1214828808.

The spelling of 1991442331 in words is "one billion, nine hundred ninety-one million, four hundred forty-two thousand, three hundred thirty-one".