21100222221 has 16 divisors (see below), whose sum is σ = 30498410880. Its totient is φ = 12898756800.

The previous prime is 21100222217. The next prime is 21100222223. The reversal of 21100222221 is 12222200112.

It is not a de Polignac number, because 21100222221 - 2² = 21100222217 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21100222221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100222223) 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, 1785606 + ... + 1797383.

It is an arithmetic number, because the mean of its divisors is an integer number (1906150680).

Almost surely, 2^21100222221 is an apocalyptic number.

It is an amenable number.

21100222221 is a deficient number, since it is larger than the sum of its proper divisors (9398188659).

21100222221 is a wasteful number, since it uses less digits than its factorization.

21100222221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3583156.

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21100222221 its reverse (12222200112), we get a palindrome (33322422333).

The spelling of 21100222221 in words is "twenty-one billion, one hundred million, two hundred twenty-two thousand, two hundred twenty-one".