221864321 has 16 divisors (see below), whose sum is σ = 260977920. Its totient is φ = 184628160.

The previous prime is 221864267. The next prime is 221864323. The reversal of 221864321 is 123468122.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 221864321 - 2¹⁰ = 221863297 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (221864323) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 216791 + ... + 217811.

It is an arithmetic number, because the mean of its divisors is an integer number (16311120).

Almost surely, 2^221864321 is an apocalyptic number.

It is an amenable number.

221864321 is a deficient number, since it is larger than the sum of its proper divisors (39113599).

221864321 is a wasteful number, since it uses less digits than its factorization.

221864321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1904.

The product of its digits is 4608, while the sum is 29.

The square root of 221864321 is about 14895.1106407438. The cubic root of 221864321 is about 605.3815147098.

The spelling of 221864321 in words is "two hundred twenty-one million, eight hundred sixty-four thousand, three hundred twenty-one".