215951 has 4 divisors (see below), whose sum is σ = 228672.
Its totient is φ = 203232.
The previous prime is 215939. The next prime is 215953. The reversal of 215951 is 159512.
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 215951 - 214 = 199567 is a prime.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (215953) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (11) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6335 + ... + 6368.
It is an arithmetic number, because the mean of its divisors is an integer number (57168).
2215951 is an apocalyptic number.
215951 is a deficient number, since it is larger than the sum of its proper divisors (12721).
215951 is a wasteful number, since it uses less digits than its factorization.
215951 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 12720.
The product of its digits is 450, while the sum is 23.
The square root of 215951 is about 464.7052829482.
The cubic root of 215951 is about 59.9954626198.
The spelling of 215951 in words is "two hundred fifteen thousand, nine hundred fifty-one".