Adding to 321640 its reverse (46123), we get a palindrome (367763).
It is a congruent number.
321640 is an untouchable number, because it is not equal to the sum of proper divisors of any number.
2321640 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 321640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (427680).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
321640 is a wasteful number, since it uses less digits than its factorization.
321640 is an evil number, because the sum of its binary digits is even.
The square root of 321640 is about 567.1331413346. The cubic root of 321640 is about 68.5156871739.
The spelling of 321640 in words is "three hundred twenty-one thousand, six hundred forty".