5981991 has 4 divisors (see below), whose sum is σ = 7975992. Its totient is φ = 3987992.

The previous prime is 5981971. The next prime is 5981993. The reversal of 5981991 is 1991895.

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

It is a cyclic number.

It is not a de Polignac number, because 5981991 - 2¹⁰ = 5980967 is a prime.

It is a D-number.

It is a plaindrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (5981993) 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 3 ways as a sum of consecutive naturals, for example, 996996 + ... + 997001.

It is an arithmetic number, because the mean of its divisors is an integer number (1993998).

Almost surely, 2^5981991 is an apocalyptic number.

5981991 is a deficient number, since it is larger than the sum of its proper divisors (1994001).

5981991 is a wasteful number, since it uses less digits than its factorization.

5981991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1994000.

The product of its digits is 29160, while the sum is 42.

The square root of 5981991 is about 2445.8109084719. The cubic root of 5981991 is about 181.5300741702.

The spelling of 5981991 in words is "five million, nine hundred eighty-one thousand, nine hundred ninety-one".