1967991 has 8 divisors (see below), whose sum is σ = 2663424. Its totient is φ = 1292280.

The previous prime is 1967947. The next prime is 1968017. The reversal of 1967991 is 1997691.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1967991 - 2⁹ = 1967479 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1967191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4695 + ... + 5096.

It is an arithmetic number, because the mean of its divisors is an integer number (332928).

2^1967991 is an apocalyptic number.

1967991 is a deficient number, since it is larger than the sum of its proper divisors (695433).

1967991 is an equidigital number, since it uses as much as digits as its factorization.

1967991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9861.

The product of its digits is 30618, while the sum is 42.

The square root of 1967991 is about 1402.8510255904. The cubic root of 1967991 is about 125.3163400896.

The spelling of 1967991 in words is "one million, nine hundred sixty-seven thousand, nine hundred ninety-one".