1990191031 has 2 divisors, whose sum is σ = 1990191032. Its totient is φ = 1990191030.

The previous prime is 1990191013. The next prime is 1990191079. The reversal of 1990191031 is 1301910991.

Together with previous prime (1990191013) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is an emirp because it is prime and its reverse (1301910991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1990191031 - 2⁷ = 1990190903 is a prime.

It is a super-2 number, since 2×1990191031² = 7921720679745685922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1990191331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995095515 + 995095516.

It is an arithmetic number, because the mean of its divisors is an integer number (995095516).

Almost surely, 2^1990191031 is an apocalyptic number.

1990191031 is a deficient number, since it is larger than the sum of its proper divisors (1).

1990191031 is an equidigital number, since it uses as much as digits as its factorization.

1990191031 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2187, while the sum is 34.

The square root of 1990191031 is about 44611.5571461028. The cubic root of 1990191031 is about 1257.8579189250.

The spelling of 1990191031 in words is "one billion, nine hundred ninety million, one hundred ninety-one thousand, thirty-one".