821916 has 54 divisors (see below), whose sum is σ = 2234960. Its totient is φ = 254592.

The previous prime is 821911. The next prime is 821939. The reversal of 821916 is 619128.

It is a super-2 number, since 2×821916² = 1351091822112, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 821916.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821911) by changing a digit.

821916 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 10365 + ... + 10443.

2⁸²¹⁹¹⁶ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 821916, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1117480).

821916 is an abundant number, since it is smaller than the sum of its proper divisors (1413044).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

821916 is a wasteful number, since it uses less digits than its factorization.

821916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123 (or 101 counting only the distinct ones).

The product of its digits is 864, while the sum is 27.

The square root of 821916 is about 906.5958305662. The cubic root of 821916 is about 93.6718602226.

The spelling of 821916 in words is "eight hundred twenty-one thousand, nine hundred sixteen".