321643840 has 168 divisors, whose sum is σ = 906380712. Its totient is φ = 108380160.

The previous prime is 321643807. The next prime is 321643867. The reversal of 321643840 is 48346123.

It can be written as a sum of positive squares in 4 ways, for example, as 59721984 + 261921856 = 7728^2 + 16184^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1144500 + ... + 1144780.

Almost surely, 2^321643840 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 321643840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (453190356).

321643840 is an abundant number, since it is smaller than the sum of its proper divisors (584736872).

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

321643840 is a wasteful number, since it uses less digits than its factorization.

321643840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 385 (or 368 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 31.

The square root of 321643840 is about 17934.4316887935. The cubic root of 321643840 is about 685.1595983815.

Adding to 321643840 its reverse (48346123), we get a palindrome (369989963).

The spelling of 321643840 in words is "three hundred twenty-one million, six hundred forty-three thousand, eight hundred forty".