821648 has 20 divisors (see below), whose sum is σ = 1612620. Its totient is φ = 405504.

The previous prime is 821647. The next prime is 821651. The reversal of 821648 is 846128.

It can be written as a sum of positive squares in 2 ways, for example, as 559504 + 262144 = 748^2 + 512^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 821648.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 821648.

It is not an unprimeable number, because it can be changed into a prime (821641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1136 + ... + 1712.

It is an arithmetic number, because the mean of its divisors is an integer number (80631).

2⁸²¹⁶⁴⁸ is an apocalyptic number.

It is an amenable number.

821648 is a deficient number, since it is larger than the sum of its proper divisors (790972).

821648 is a wasteful number, since it uses less digits than its factorization.

821648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 674 (or 668 counting only the distinct ones).

The product of its digits is 3072, while the sum is 29.

The square root of 821648 is about 906.4480128502. The cubic root of 821648 is about 93.6616780030.

The spelling of 821648 in words is "eight hundred twenty-one thousand, six hundred forty-eight".