821895 has 16 divisors (see below), whose sum is σ = 1327200. Its totient is φ = 434304.

The previous prime is 821879. The next prime is 821897. The reversal of 821895 is 598128.

It is a happy number.

It is not a de Polignac number, because 821895 - 2⁴ = 821879 is a prime.

It is a super-2 number, since 2×821895² = 1351022782050, which contains 22 as substring.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821897) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2181 + ... + 2529.

It is an arithmetic number, because the mean of its divisors is an integer number (82950).

2⁸²¹⁸⁹⁵ is an apocalyptic number.

821895 is a deficient number, since it is larger than the sum of its proper divisors (505305).

821895 is a wasteful number, since it uses less digits than its factorization.

821895 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 514.

The product of its digits is 5760, while the sum is 33.

The square root of 821895 is about 906.5842487050. The cubic root of 821895 is about 93.6710624421.

The spelling of 821895 in words is "eight hundred twenty-one thousand, eight hundred ninety-five".