891921 has 8 divisors (see below), whose sum is σ = 1199104. Its totient is φ = 589680.

The previous prime is 891907. The next prime is 891923. The reversal of 891921 is 129198.

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

It is not a de Polignac number, because 891921 - 2⁵ = 891889 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 891921.

It is not an unprimeable number, because it can be changed into a prime (891923) 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, 790 + ... + 1551.

It is an arithmetic number, because the mean of its divisors is an integer number (149888).

2⁸⁹¹⁹²¹ is an apocalyptic number.

It is an amenable number.

891921 is a deficient number, since it is larger than the sum of its proper divisors (307183).

891921 is a wasteful number, since it uses less digits than its factorization.

891921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2471.

The product of its digits is 1296, while the sum is 30.

The square root of 891921 is about 944.4156923728. The cubic root of 891921 is about 96.2591738037.

The spelling of 891921 in words is "eight hundred ninety-one thousand, nine hundred twenty-one".