1005991 has 8 divisors (see below), whose sum is σ = 1159200. Its totient is φ = 855168.

The previous prime is 1005989. The next prime is 1006003. The reversal of 1005991 is 1995001.

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

It is a cyclic number.

It is not a de Polignac number, because 1005991 - 2¹ = 1005989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1005911) 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, 435 + ... + 1483.

It is an arithmetic number, because the mean of its divisors is an integer number (144900).

2^1005991 is an apocalyptic number.

1005991 is a deficient number, since it is larger than the sum of its proper divisors (153209).

1005991 is a wasteful number, since it uses less digits than its factorization.

1005991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1193.

The product of its (nonzero) digits is 405, while the sum is 25.

The square root of 1005991 is about 1002.9910268791. The cubic root of 1005991 is about 100.1993025212.

The spelling of 1005991 in words is "one million, five thousand, nine hundred ninety-one".