1991442031 has 2 divisors, whose sum is σ = 1991442032. Its totient is φ = 1991442030.

The previous prime is 1991442007. The next prime is 1991442043. The reversal of 1991442031 is 1302441991.

It is a strong prime.

It is an emirp because it is prime and its reverse (1302441991) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1991442031 is a prime.

It is a super-2 number, since 2×1991442031² = 7931682725666809922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1991442331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995721015 + 995721016.

It is an arithmetic number, because the mean of its divisors is an integer number (995721016).

Almost surely, 2^1991442031 is an apocalyptic number.

1991442031 is a deficient number, since it is larger than the sum of its proper divisors (1).

1991442031 is an equidigital number, since it uses as much as digits as its factorization.

1991442031 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 1991442031 is about 44625.5759738740. The cubic root of 1991442031 is about 1258.1214197044.

The spelling of 1991442031 in words is "one billion, nine hundred ninety-one million, four hundred forty-two thousand, thirty-one".