1027991 has 4 divisors (see below), whose sum is σ = 1061184. Its totient is φ = 994800.

The previous prime is 1027987. The next prime is 1028003. The reversal of 1027991 is 1997201.

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 1027991 - 2² = 1027987 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1027931) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16550 + ... + 16611.

It is an arithmetic number, because the mean of its divisors is an integer number (265296).

2^1027991 is an apocalyptic number.

1027991 is a deficient number, since it is larger than the sum of its proper divisors (33193).

1027991 is an equidigital number, since it uses as much as digits as its factorization.

1027991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33192.

The product of its (nonzero) digits is 1134, while the sum is 29.

The square root of 1027991 is about 1013.8989101483. The cubic root of 1027991 is about 100.9244607214.

The spelling of 1027991 in words is "one million, twenty-seven thousand, nine hundred ninety-one".