821449728 has 352 divisors, whose sum is σ = 2762958720. Its totient is φ = 238878720.

The previous prime is 821449711. The next prime is 821449751. The reversal of 821449728 is 827944128.

It is a tau number, because it is divible by the number of its divisors (352).

Its product of digits (258048) is a multiple of the sum of its prime divisors (126).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11252700 + ... + 11252772.

Almost surely, 2^821449728 is an apocalyptic number.

821449728 is a gapful number since it is divisible by the number (88) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 821449728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1381479360).

821449728 is an abundant number, since it is smaller than the sum of its proper divisors (1941508992).

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

821449728 is a wasteful number, since it uses less digits than its factorization.

821449728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150 (or 126 counting only the distinct ones).

The product of its digits is 258048, while the sum is 45.

The square root of 821449728 is about 28660.9442970744. The cubic root of 821449728 is about 936.5414355919.

The spelling of 821449728 in words is "eight hundred twenty-one million, four hundred forty-nine thousand, seven hundred twenty-eight".