215531221 has 8 divisors (see below), whose sum is σ = 218973888. Its totient is φ = 212100000.

The previous prime is 215531203. The next prime is 215531233. The reversal of 215531221 is 122135512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 215531221 - 2¹¹ = 215529173 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 215531192 and 215531201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215531021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40146 + ... + 45196.

It is an arithmetic number, because the mean of its divisors is an integer number (27371736).

Almost surely, 2^215531221 is an apocalyptic number.

It is an amenable number.

215531221 is a deficient number, since it is larger than the sum of its proper divisors (3442667).

215531221 is an equidigital number, since it uses as much as digits as its factorization.

215531221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5723.

The product of its digits is 600, while the sum is 22.

The square root of 215531221 is about 14680.9816088707. The cubic root of 215531221 is about 599.5656309855.

Adding to 215531221 its reverse (122135512), we get a palindrome (337666733).

The spelling of 215531221 in words is "two hundred fifteen million, five hundred thirty-one thousand, two hundred twenty-one".