821279 has 4 divisors (see below), whose sum is σ = 824376. Its totient is φ = 818184.

The previous prime is 821263. The next prime is 821281. The reversal of 821279 is 972128.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 821279 - 2⁴ = 821263 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821209) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1109 + ... + 1694.

It is an arithmetic number, because the mean of its divisors is an integer number (206094).

2⁸²¹²⁷⁹ is an apocalyptic number.

821279 is a deficient number, since it is larger than the sum of its proper divisors (3097).

821279 is a wasteful number, since it uses less digits than its factorization.

821279 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3096.

The product of its digits is 2016, while the sum is 29.

The square root of 821279 is about 906.2444482589. The cubic root of 821279 is about 93.6476548308.

The spelling of 821279 in words is "eight hundred twenty-one thousand, two hundred seventy-nine".