891021 has 8 divisors (see below), whose sum is σ = 1257984. Its totient is φ = 559040.

The previous prime is 891017. The next prime is 891047. The reversal of 891021 is 120198.

891021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 891021 - 2² = 891017 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (891001) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8685 + ... + 8786.

It is an arithmetic number, because the mean of its divisors is an integer number (157248).

2⁸⁹¹⁰²¹ is an apocalyptic number.

It is an amenable number.

891021 is a deficient number, since it is larger than the sum of its proper divisors (366963).

891021 is a wasteful number, since it uses less digits than its factorization.

891021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17491.

The product of its (nonzero) digits is 144, while the sum is 21.

The square root of 891021 is about 943.9390870178. The cubic root of 891021 is about 96.2267858785.

The spelling of 891021 in words is "eight hundred ninety-one thousand, twenty-one".