221430021 has 4 divisors (see below), whose sum is σ = 295240032. Its totient is φ = 147620012.

The previous prime is 221430007. The next prime is 221430023. The reversal of 221430021 is 120034122.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 221430021 - 2¹⁰ = 221428997 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221430023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36905001 + ... + 36905006.

It is an arithmetic number, because the mean of its divisors is an integer number (73810008).

Almost surely, 2^221430021 is an apocalyptic number.

It is an amenable number.

221430021 is a deficient number, since it is larger than the sum of its proper divisors (73810011).

221430021 is an equidigital number, since it uses as much as digits as its factorization.

221430021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73810010.

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 221430021 is about 14880.5248899358. The cubic root of 221430021 is about 604.9862447070.

Adding to 221430021 its reverse (120034122), we get a palindrome (341464143).

The spelling of 221430021 in words is "two hundred twenty-one million, four hundred thirty thousand, twenty-one".