221009213 has 4 divisors (see below), whose sum is σ = 221210688. Its totient is φ = 220807740.

The previous prime is 221009209. The next prime is 221009219. The reversal of 221009213 is 312900122.

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 221009213 - 2² = 221009209 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221009219) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99083 + ... + 101288.

It is an arithmetic number, because the mean of its divisors is an integer number (55302672).

Almost surely, 2^221009213 is an apocalyptic number.

It is an amenable number.

221009213 is a deficient number, since it is larger than the sum of its proper divisors (201475).

221009213 is a wasteful number, since it uses less digits than its factorization.

221009213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201474.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 221009213 is about 14866.3786108117. The cubic root of 221009213 is about 604.6027608840.

Adding to 221009213 its reverse (312900122), we get a palindrome (533909335).

It can be divided in two parts, 22100 and 9213, that added together give a palindrome (31313).

The spelling of 221009213 in words is "two hundred twenty-one million, nine thousand, two hundred thirteen".