321721872 has 160 divisors (see below), whose sum is σ = 922762368. Its totient is φ = 96165888.

The previous prime is 321721859. The next prime is 321721913. The reversal of 321721872 is 278127123.

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, 1859578 + ... + 1859750.

Almost surely, 2^321721872 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 321721872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (461381184).

321721872 is an abundant number, since it is smaller than the sum of its proper divisors (601040496).

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

321721872 is a wasteful number, since it uses less digits than its factorization.

321721872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 297 (or 291 counting only the distinct ones).

The product of its digits is 9408, while the sum is 33.

The square root of 321721872 is about 17936.6070370067. The cubic root of 321721872 is about 685.2150013295.

Adding to 321721872 its reverse (278127123), we get a palindrome (599848995).

The spelling of 321721872 in words is "three hundred twenty-one million, seven hundred twenty-one thousand, eight hundred seventy-two".