21206222 has 4 divisors (see below), whose sum is σ = 31809336. Its totient is φ = 10603110.

The previous prime is 21206219. The next prime is 21206233. The reversal of 21206222 is 22260212.

It is a semiprime because it is the product of two primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21206222.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5301554 + ... + 5301557.

It is an arithmetic number, because the mean of its divisors is an integer number (7952334).

Almost surely, 2^21206222 is an apocalyptic number.

21206222 is a deficient number, since it is larger than the sum of its proper divisors (10603114).

21206222 is a wasteful number, since it uses less digits than its factorization.

21206222 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10603113.

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 21206222 is about 4605.0213897440. The cubic root of 21206222 is about 276.7925741016.

Adding to 21206222 its reverse (22260212), we get a palindrome (43466434).

The spelling of 21206222 in words is "twenty-one million, two hundred six thousand, two hundred twenty-two".