1991508031 has 2 divisors, whose sum is σ = 1991508032. Its totient is φ = 1991508030.

The previous prime is 1991507941. The next prime is 1991508041. The reversal of 1991508031 is 1308051991.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1991508031 - 2¹¹ = 1991505983 is a prime.

It is a super-2 number, since 2×1991508031² = 7932208475074993922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1991508041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995754015 + 995754016.

It is an arithmetic number, because the mean of its divisors is an integer number (995754016).

Almost surely, 2^1991508031 is an apocalyptic number.

1991508031 is a deficient number, since it is larger than the sum of its proper divisors (1).

1991508031 is an equidigital number, since it uses as much as digits as its factorization.

1991508031 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9720, while the sum is 37.

The square root of 1991508031 is about 44626.3154540009. The cubic root of 1991508031 is about 1258.1353183592.

The spelling of 1991508031 in words is "one billion, nine hundred ninety-one million, five hundred eight thousand, thirty-one".