1991507941 has 2 divisors, whose sum is σ = 1991507942. Its totient is φ = 1991507940.

The previous prime is 1991507929. The next prime is 1991508031. The reversal of 1991507941 is 1497051991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1717770916 + 273737025 = 41446^2 + 16545^2 .

It is a cyclic number.

It is not a de Polignac number, because 1991507941 - 2⁵ = 1991507909 is a prime.

It is a super-2 number, since 2×1991507941² = 7932207758132118962, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1991507891 and 1991507900.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1991507911) 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, 995753970 + 995753971.

It is an arithmetic number, because the mean of its divisors is an integer number (995753971).

Almost surely, 2^1991507941 is an apocalyptic number.

It is an amenable number.

1991507941 is a deficient number, since it is larger than the sum of its proper divisors (1).

1991507941 is an equidigital number, since it uses as much as digits as its factorization.

1991507941 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 102060, while the sum is 46.

The square root of 1991507941 is about 44626.3144456273. The cubic root of 1991507941 is about 1258.1352994067.

The spelling of 1991507941 in words is "one billion, nine hundred ninety-one million, five hundred seven thousand, nine hundred forty-one".