221215555 has 8 divisors (see below), whose sum is σ = 289591344. Its totient is φ = 160884000.

The previous prime is 221215529. The next prime is 221215571. The reversal of 221215555 is 555512122.

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

It is not a de Polignac number, because 221215555 - 2⁵ = 221215523 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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, 2010996 + ... + 2011105.

It is an arithmetic number, because the mean of its divisors is an integer number (36198918).

Almost surely, 2^221215555 is an apocalyptic number.

221215555 is a deficient number, since it is larger than the sum of its proper divisors (68375789).

221215555 is a wasteful number, since it uses less digits than its factorization.

221215555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4022117.

The product of its digits is 5000, while the sum is 28.

The square root of 221215555 is about 14873.3168795666. The cubic root of 221215555 is about 604.7908618476.

Adding to 221215555 its reverse (555512122), we get a palindrome (776727677).

It can be divided in two parts, 2212 and 15555, that multiplied together give a triangular number (34407660 = T₈₂₉₅).

The spelling of 221215555 in words is "two hundred twenty-one million, two hundred fifteen thousand, five hundred fifty-five".