867991 has 2 divisors, whose sum is σ = 867992. Its totient is φ = 867990.

The previous prime is 867959. The next prime is 868019. The reversal of 867991 is 199768.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 867991 - 2⁵ = 867959 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (867091) 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 as a sum of consecutive naturals, namely, 433995 + 433996.

It is an arithmetic number, because the mean of its divisors is an integer number (433996).

2⁸⁶⁷⁹⁹¹ is an apocalyptic number.

867991 is a deficient number, since it is larger than the sum of its proper divisors (1).

867991 is an equidigital number, since it uses as much as digits as its factorization.

867991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27216, while the sum is 40.

The square root of 867991 is about 931.6603458343. The cubic root of 867991 is about 95.3904887622.

The spelling of 867991 in words is "eight hundred sixty-seven thousand, nine hundred ninety-one".