21221022221 has 16 divisors (see below), whose sum is σ = 24496889088. Its totient is φ = 18007056000.

The previous prime is 21221022167. The next prime is 21221022239. The reversal of 21221022221 is 12222012212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21221022221 - 2¹⁰ = 21221021197 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21221022221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221022421) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 275441 + ... + 343961.

It is an arithmetic number, because the mean of its divisors is an integer number (1531055568).

Almost surely, 2^21221022221 is an apocalyptic number.

It is an amenable number.

21221022221 is a deficient number, since it is larger than the sum of its proper divisors (3275866867).

21221022221 is a wasteful number, since it uses less digits than its factorization.

21221022221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68972.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21221022221 its reverse (12222012212), we get a palindrome (33443034433).

The spelling of 21221022221 in words is "twenty-one billion, two hundred twenty-one million, twenty-two thousand, two hundred twenty-one".