It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1623 = 3 ⋅541.
It is an Ulam number.
It is a D-number.
It is a Duffinian number.
3261 is a lucky number.
It is a plaindrome in base 7 and base 14.
It is a nialpdrome in base 15.
It is a congruent number.
23261 is an apocalyptic number.
It is an amenable number.
3261 is a wasteful number, since it uses less digits than its factorization.
3261 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 1090.
The square root of 3261 is about 57.1051661411. The cubic root of 3261 is about 14.8291730397.
Subtracting from 3261 its sum of digits (12), we obtain a square (3249 = 572).
Adding to 3261 its reverse (1623), we get a palindrome (4884).
The spelling of 3261 in words is "three thousand, two hundred sixty-one".