821105 has 8 divisors (see below), whose sum is σ = 996072. Its totient is φ = 649728.

The previous prime is 821101. The next prime is 821113. The reversal of 821105 is 501128.

821105 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 44944 + 776161 = 212^2 + 881^2 .

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 821105 - 2² = 821101 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 15.

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (821101) 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, 362 + ... + 1331.

It is an arithmetic number, because the mean of its divisors is an integer number (124509).

2⁸²¹¹⁰⁵ is an apocalyptic number.

It is an amenable number.

821105 is a deficient number, since it is larger than the sum of its proper divisors (174967).

821105 is a wasteful number, since it uses less digits than its factorization.

821105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1795.

The product of its (nonzero) digits is 80, while the sum is 17.

The square root of 821105 is about 906.1484425854. The cubic root of 821105 is about 93.6410408207.

The spelling of 821105 in words is "eight hundred twenty-one thousand, one hundred five".