215455221 has 28 divisors (see below), whose sum is σ = 324363052. Its totient is φ = 143047296.

The previous prime is 215455211. The next prime is 215455243. The reversal of 215455221 is 122554512.

It can be written as a sum of positive squares in 2 ways, for example, as 122544900 + 92910321 = 11070^2 + 9639^2 .

It is not a de Polignac number, because 215455221 - 2⁵ = 215455189 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215455211) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 245235 + ... + 246111.

Almost surely, 2^215455221 is an apocalyptic number.

It is an amenable number.

215455221 is a deficient number, since it is larger than the sum of its proper divisors (108907831).

215455221 is an frugal number, since it uses more digits than its factorization.

215455221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1232 (or 1217 counting only the distinct ones).

The product of its digits is 4000, while the sum is 27.

The square root of 215455221 is about 14678.3929978728. The cubic root of 215455221 is about 599.4951503305.

It can be divided in two parts, 2154 and 55221, that added together give a palindrome (57375).

The spelling of 215455221 in words is "two hundred fifteen million, four hundred fifty-five thousand, two hundred twenty-one".