891001 has 2 divisors, whose sum is σ = 891002. Its totient is φ = 891000.

The previous prime is 890999. The next prime is 891017. The reversal of 891001 is 100198.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 640000 + 251001 = 800^2 + 501^2 .

It is a cyclic number.

It is not a de Polignac number, because 891001 - 2¹ = 890999 is a prime.

Together with 890999, it forms a pair of twin primes.

It is equal to p₇₀₆₂₄ and since 891001 and 70624 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 891001.

It is not a weakly prime, because it can be changed into another prime (891061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 445500 + 445501.

It is an arithmetic number, because the mean of its divisors is an integer number (445501).

2⁸⁹¹⁰⁰¹ is an apocalyptic number.

It is an amenable number.

891001 is a deficient number, since it is larger than the sum of its proper divisors (1).

891001 is an equidigital number, since it uses as much as digits as its factorization.

891001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 19.

The square root of 891001 is about 943.9284930544. The cubic root of 891001 is about 96.2260658991.

Adding to 891001 its reverse (100198), we get a palindrome (991199).

The spelling of 891001 in words is "eight hundred ninety-one thousand, one".