It is a happy number.
It is a plaindrome in base 13.
It is a congruent number.
7900 is an untouchable number, because it is not equal to the sum of proper divisors of any number.
27900 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 7900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8680).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
7900 is a wasteful number, since it uses less digits than its factorization.
7900 is an odious number, because the sum of its binary digits is odd.
The square root of 7900 is about 88.8819441732. The cubic root of 7900 is about 19.9163170129.
Adding to 7900 its reverse (97), we get a palindrome (7997).
The spelling of 7900 in words is "seven thousand, nine hundred".