1640 is nontrivially palindromic in base 3 and base 9.
1640 is an undulating number in base 3.
1640 is a nontrivial repdigit in base 9.
It is a plaindrome in base 9 and base 16.
It is a nialpdrome in base 9, base 13 and base 14.
It is a zygodrome in base 9.
It is a congruent number.
It is an unprimeable number.
21640 is an apocalyptic number.
1640 is a gapful number since it is divisible by the number (10) 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 1640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1890).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
1640 is a wasteful number, since it uses less digits than its factorization.
1640 is an odious number, because the sum of its binary digits is odd.
The square root of 1640 is about 40.4969134626. The cubic root of 1640 is about 11.7927370799.
The spelling of 1640 in words is "one thousand, six hundred forty".