821712 has 80 divisors (see below), whose sum is σ = 2410560. Its totient is φ = 239616.

The previous prime is 821677. The next prime is 821741. The reversal of 821712 is 217128.

It is a super-2 number, since 2×821712² = 1350421221888, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15478 + ... + 15530.

It is an arithmetic number, because the mean of its divisors is an integer number (30132).

2⁸²¹⁷¹² 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 821712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1205280).

821712 is an abundant number, since it is smaller than the sum of its proper divisors (1588848).

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

821712 is a wasteful number, since it uses less digits than its factorization.

821712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 100 (or 94 counting only the distinct ones).

The product of its digits is 224, while the sum is 21.

The square root of 821712 is about 906.4833147940. The cubic root of 821712 is about 93.6641097791.

The spelling of 821712 in words is "eight hundred twenty-one thousand, seven hundred twelve".