921891 has 8 divisors (see below), whose sum is σ = 1233664. Its totient is φ = 612360.

The previous prime is 921889. The next prime is 921901. The reversal of 921891 is 198129.

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

It is not a de Polignac number, because 921891 - 2¹ = 921889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (921821) 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, 1146 + ... + 1776.

It is an arithmetic number, because the mean of its divisors is an integer number (154208).

2⁹²¹⁸⁹¹ is an apocalyptic number.

921891 is a deficient number, since it is larger than the sum of its proper divisors (311773).

921891 is a wasteful number, since it uses less digits than its factorization.

921891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1121.

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

The square root of 921891 is about 960.1515505377. The cubic root of 921891 is about 97.3254734484.

It can be divided in two parts, 9218 and 91, that multiplied together give a palindrome (838838).

The spelling of 921891 in words is "nine hundred twenty-one thousand, eight hundred ninety-one".