1991011937 has 2 divisors, whose sum is σ = 1991011938. Its totient is φ = 1991011936.

The previous prime is 1991011931. The next prime is 1991011987. The reversal of 1991011937 is 7391101991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1889727841 + 101284096 = 43471^2 + 10064^2 .

It is a cyclic number.

It is not a de Polignac number, because 1991011937 - 2⁸ = 1991011681 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1991011894 and 1991011903.

It is not a weakly prime, because it can be changed into another prime (1991011931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995505968 + 995505969.

It is an arithmetic number, because the mean of its divisors is an integer number (995505969).

Almost surely, 2^1991011937 is an apocalyptic number.

It is an amenable number.

1991011937 is a deficient number, since it is larger than the sum of its proper divisors (1).

1991011937 is an equidigital number, since it uses as much as digits as its factorization.

1991011937 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15309, while the sum is 41.

The square root of 1991011937 is about 44620.7567954646. The cubic root of 1991011937 is about 1258.0308405453.

The spelling of 1991011937 in words is "one billion, nine hundred ninety-one million, eleven thousand, nine hundred thirty-seven".