1650 is an esthetic number in base 7, because in such base its adjacent digits differ by 1.
It is an alternating number because its digits alternate between odd and even.
1650 is an undulating number in base 7.
It is a Curzon number.
It is a plaindrome in base 9 and base 13.
It is a nialpdrome in base 15.
It is a zygodrome in base 9.
1650 is an untouchable number, because it is not equal to the sum of proper divisors of any number.
1650 is a gapful number since it is divisible by the number (10) formed by its first and last digit.
It is a practical number, because each smaller number is the sum of distinct divisors of 1650, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2232).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
1650 is a wasteful number, since it uses less digits than its factorization.
1650 is an evil number, because the sum of its binary digits is even.
The square root of 1650 is about 40.6201920232. The cubic root of 1650 is about 11.8166575047.
1650 divided by its product of nonzero digits (30) gives a palindrome (55).
Adding to 1650 its reverse (561), we get a triangular number (2211 = T66).
Subtracting from 1650 its reverse (561), we obtain a square (1089 = 332).
The spelling of 1650 in words is "one thousand, six hundred fifty".