• 215 can be written using four 4's:
215 has 4 divisors (see below), whose sum is σ = 264. Its totient is φ = 168.
The previous prime is 211. The next prime is 223. The reversal of 215 is 512.
215 is nontrivially palindromic in base 4 and base 6.
It is a Cunningham number, because it is equal to 63-1.
It is a semiprime because it is the product of two primes.
It is a cyclic number.
It is not a de Polignac number, because 215 - 22 = 211 is a prime.
It is a Duffinian number.
215 is a nontrivial repdigit in base 6.
It is a plaindrome in base 6, base 9, base 12, base 13 and base 14.
It is a nialpdrome in base 6, base 15 and base 16.
It is a zygodrome in base 6.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (211) by changing a digit.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17 + ... + 26.
It is an arithmetic number, because the mean of its divisors is an integer number (66).
215 is a deficient number, since it is larger than the sum of its proper divisors (49).
215 is an equidigital number, since it uses as much as digits as its factorization.
215 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 48.
The product of its digits is 10, while the sum is 8.
The square root of 215 is about 14.6628782986. The cubic root of 215 is about 5.9907264149.
Adding to 215 its product of digits (10), we get a square (225 = 152).
Adding to 215 its reverse (512), we get a palindrome (727).
It can be divided in two parts, 21 and 5, that multiplied together give a triangular number (105 = T14).
The spelling of 215 in words is "two hundred fifteen", and thus it is an aban number.
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