221310021 has 4 divisors (see below), whose sum is σ = 295080032. Its totient is φ = 147540012.

The previous prime is 221309989. The next prime is 221310031. The reversal of 221310021 is 120013122.

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 not a de Polignac number, because 221310021 - 2⁵ = 221309989 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221309979 and 221310006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221310031) 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 3 ways as a sum of consecutive naturals, for example, 36885001 + ... + 36885006.

It is an arithmetic number, because the mean of its divisors is an integer number (73770008).

Almost surely, 2^221310021 is an apocalyptic number.

It is an amenable number.

221310021 is a deficient number, since it is larger than the sum of its proper divisors (73770011).

221310021 is an equidigital number, since it uses as much as digits as its factorization.

221310021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73770010.

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 221310021 is about 14876.4922276725. The cubic root of 221310021 is about 604.8769378366.

Adding to 221310021 its reverse (120013122), we get a palindrome (341323143).

The spelling of 221310021 in words is "two hundred twenty-one million, three hundred ten thousand, twenty-one".