215557221 has 8 divisors (see below), whose sum is σ = 313537824. Its totient is φ = 130640720.

The previous prime is 215557217. The next prime is 215557249. The reversal of 215557221 is 122755512.

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 215557221 - 2² = 215557217 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215557211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3265986 + ... + 3266051.

It is an arithmetic number, because the mean of its divisors is an integer number (39192228).

Almost surely, 2^215557221 is an apocalyptic number.

It is an amenable number.

215557221 is a deficient number, since it is larger than the sum of its proper divisors (97980603).

215557221 is a wasteful number, since it uses less digits than its factorization.

215557221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6532051.

The product of its digits is 7000, while the sum is 30.

The square root of 215557221 is about 14681.8670815397. The cubic root of 215557221 is about 599.5897389849.

The spelling of 215557221 in words is "two hundred fifteen million, five hundred fifty-seven thousand, two hundred twenty-one".