321628720 has 160 divisors (see below), whose sum is σ = 895942656. Its totient is φ = 105062400.

The previous prime is 321628709. The next prime is 321628733. The reversal of 321628720 is 27826123.

It is a Harshad number since it is a multiple of its sum of digits (31).

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 31 ways as a sum of consecutive naturals, for example, 1683825 + ... + 1684015.

Almost surely, 2^321628720 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 321628720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (447971328).

321628720 is an abundant number, since it is smaller than the sum of its proper divisors (574313936).

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

321628720 is a wasteful number, since it uses less digits than its factorization.

321628720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 339 (or 333 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 31.

The square root of 321628720 is about 17934.0101483188. The cubic root of 321628720 is about 685.1488621010.

The spelling of 321628720 in words is "three hundred twenty-one million, six hundred twenty-eight thousand, seven hundred twenty".