221621212 has 12 divisors (see below), whose sum is σ = 389503296. Its totient is φ = 110334560.

The previous prime is 221621177. The next prime is 221621221. The reversal of 221621212 is 212126122.

It is a self number, because there is not a number n which added to its sum of digits gives 221621212.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 117964 + ... + 119827.

It is an arithmetic number, because the mean of its divisors is an integer number (32458608).

Almost surely, 2^221621212 is an apocalyptic number.

It is an amenable number.

221621212 is a deficient number, since it is larger than the sum of its proper divisors (167882084).

221621212 is a wasteful number, since it uses less digits than its factorization.

221621212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 238028 (or 238026 counting only the distinct ones).

The product of its digits is 192, while the sum is 19.

The square root of 221621212 is about 14886.9477059604. The cubic root of 221621212 is about 605.1603172347.

Adding to 221621212 its reverse (212126122), we get a palindrome (433747334).

The spelling of 221621212 in words is "two hundred twenty-one million, six hundred twenty-one thousand, two hundred twelve".