It is an alternating number because its digits alternate between odd and even.
It is a plaindrome in base 13.
It is a self number, because there is not a number n which added to its sum of digits gives 7890.
It is an unprimeable number.
7890 is an untouchable number, because it is not equal to the sum of proper divisors of any number.
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
7890 is a wasteful number, since it uses less digits than its factorization.
7890 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 273.
The square root of 7890 is about 88.8256719648. The cubic root of 7890 is about 19.9079099553.
Subtracting from 7890 its reverse (987), we obtain a triangular number (6903 = T117).
The spelling of 7890 in words is "seven thousand, eight hundred ninety".