821990 has 16 divisors (see below), whose sum is σ = 1593648. Its totient is φ = 303456.

The previous prime is 821971. The next prime is 821993. The reversal of 821990 is 99128.

821990 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821993) 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, 3032 + ... + 3291.

It is an arithmetic number, because the mean of its divisors is an integer number (99603).

2⁸²¹⁹⁹⁰ is an apocalyptic number.

821990 is a deficient number, since it is larger than the sum of its proper divisors (771658).

821990 is a wasteful number, since it uses less digits than its factorization.

821990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6343.

The product of its (nonzero) digits is 1296, while the sum is 29.

The square root of 821990 is about 906.6366416597. The cubic root of 821990 is about 93.6746713411.

The spelling of 821990 in words is "eight hundred twenty-one thousand, nine hundred ninety".