• 841 can be written using four 4's:
841 has 3 divisors (see below), whose sum is σ = 871. Its totient is φ = 812.
The previous prime is 839. The next prime is 853. The reversal of 841 is 148.
The square root of 841 is 29.
It is a perfect power (a square), and thus also a powerful number.
841 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.
It can be written as a sum of positive squares in only one way, i.e., 441 + 400 = 21^2 + 20^2 .
It is not a de Polignac number, because 841 - 21 = 839 is a prime.
It is a Duffinian number.
841 is a lucky number.
It is a plaindrome in base 9 and base 16.
It is a nialpdrome in base 10 and base 14.
It is not an unprimeable number, because it can be changed into a prime (811) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (5) of ones.
It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 15 + ... + 43.
2841 is an apocalyptic number.
841 is the 29-th square number.
841 is the 21-st centered square number, the 16-th centered heptagonal number and also the 15-th centered octagonal number.
It is an amenable number.
841 is a deficient number, since it is larger than the sum of its proper divisors (30).
841 is an equidigital number, since it uses as much as digits as its factorization.
841 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 58 (or 29 counting only the distinct ones).
The product of its digits is 32, while the sum is 13.
The cubic root of 841 is about 9.4391306774.
Subtracting from 841 its sum of digits (13), we obtain a palindrome (828).
Adding to 841 its reverse (148), we get a palindrome (989).
It can be divided in two parts, 8 and 41, that added together give a square (49 = 72).
The spelling of 841 in words is "eight hundred forty-one", and thus it is an aban number.
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