821090 has 16 divisors (see below), whose sum is σ = 1510272. Its totient is φ = 321264.

The previous prime is 821089. The next prime is 821099. The reversal of 821090 is 90128.

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 (821099) 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, 404 + ... + 1343.

It is an arithmetic number, because the mean of its divisors is an integer number (94392).

2⁸²¹⁰⁹⁰ is an apocalyptic number.

821090 is a deficient number, since it is larger than the sum of its proper divisors (689182).

821090 is a wasteful number, since it uses less digits than its factorization.

821090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1801.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 821090 is about 906.1401657580. The cubic root of 821090 is about 93.6404706037.

The spelling of 821090 in words is "eight hundred twenty-one thousand, ninety".