321728456640 has 224 divisors, whose sum is σ = 1026422046720. Its totient is φ = 85381021696.

The previous prime is 321728456603. The next prime is 321728456657. The reversal of 321728456640 is 46654827123.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 321728456640.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 264361312 + ... + 264362528.

It is an arithmetic number, because the mean of its divisors is an integer number (4582241280).

Almost surely, 2^321728456640 is an apocalyptic number.

321728456640 is a gapful number since it is divisible by the number (30) 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 321728456640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (513211023360).

321728456640 is an abundant number, since it is smaller than the sum of its proper divisors (704693590080).

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

321728456640 is a wasteful number, since it uses less digits than its factorization.

321728456640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2339 (or 2329 counting only the distinct ones).

The product of its (nonzero) digits is 1935360, while the sum is 48.

The spelling of 321728456640 in words is "three hundred twenty-one billion, seven hundred twenty-eight million, four hundred fifty-six thousand, six hundred forty".