1991011933 has 4 divisors (see below), whose sum is σ = 2108130300. Its totient is φ = 1873893568.

The previous prime is 1991011931. The next prime is 1991011937. The reversal of 1991011933 is 3391101991.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1148735449 + 842276484 = 33893^2 + 29022^2 .

It is a cyclic number.

It is not a de Polignac number, because 1991011933 - 2¹ = 1991011931 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1991011892 and 1991011901.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991011931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 58559158 + ... + 58559191.

It is an arithmetic number, because the mean of its divisors is an integer number (527032575).

Almost surely, 2^1991011933 is an apocalyptic number.

It is an amenable number.

1991011933 is a deficient number, since it is larger than the sum of its proper divisors (117118367).

1991011933 is a wasteful number, since it uses less digits than its factorization.

1991011933 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117118366.

The product of its (nonzero) digits is 6561, while the sum is 37.

The square root of 1991011933 is about 44620.7567506424. The cubic root of 1991011933 is about 1258.0308397029.

The spelling of 1991011933 in words is "one billion, nine hundred ninety-one million, eleven thousand, nine hundred thirty-three".