321897728 has 36 divisors (see below), whose sum is σ = 646711380. Its totient is φ = 159903744.

The previous prime is 321897727. The next prime is 321897731. The reversal of 321897728 is 827798123.

It can be written as a sum of positive squares in 2 ways, for example, as 150601984 + 171295744 = 12272^2 + 13088^2 .

It is a super-3 number, since 3×321897728³ (a number of 27 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (321897721) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36188 + ... + 44196.

It is an arithmetic number, because the mean of its divisors is an integer number (17964205).

Almost surely, 2^321897728 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 321897728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (323355690).

321897728 is an abundant number, since it is smaller than the sum of its proper divisors (324813652).

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

321897728 is an equidigital number, since it uses as much as digits as its factorization.

321897728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8182 (or 8168 counting only the distinct ones).

The product of its digits is 338688, while the sum is 47.

The square root of 321897728 is about 17941.5085207460. The cubic root of 321897728 is about 685.3398267674.

The spelling of 321897728 in words is "three hundred twenty-one million, eight hundred ninety-seven thousand, seven hundred twenty-eight".