247 can be written using four 4's:
See also 113
247 has 4
divisors (see below), whose sum is σ = 280
Its totient is φ = 216
The previous prime is 241. The next prime is 251. The reversal of 247 is 742.
It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.
It is a 3-Lehmer number, since φ(247) divides (247-1)3.
It is a cyclic number.
It is not a de Polignac number, because 247 - 23 = 239 is a prime.
It is a super-2 number, since 2×2472 = 122018, which contains 22 as substring.
It is a Harshad number since it is a multiple of its sum of digits (13), and also a Moran number because the ratio is a prime number: 19 = 247 / (2 + 4 + 7).
It is a Duffinian number.
It is a plaindrome in base 8, base 10, base 14 and base 15.
It is a nialpdrome in base 16.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (241) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (7) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4 + ... + 22.
It is equal to the Eulerian number A(8, 1).
It is an arithmetic number, because the mean of its divisors is an integer number (70).
2247 is an apocalyptic number.
247 is the 13-th pentagonal number.
247 is a deficient number, since it is larger than the sum of its proper divisors (33).
247 is a wasteful number, since it uses less digits than its factorization.
247 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 32.
The product of its digits is 56, while the sum is 13.
The square root of 247 is about 15.7162336455.
The cubic root of 247 is about 6.2743053574.
Adding to 247 its product of digits (56), we get a palindrome (303).
Subtracting from 247 its product of digits (56), we obtain a palindrome (191).
Adding to 247 its reverse (742), we get a palindrome (989).
It can be divided in two parts, 2 and 47, that added together give a square (49 = 72).
The spelling of 247 in words is "two hundred forty-seven", and thus it is an aban number and an iban number.