21102220221 has 8 divisors (see below), whose sum is σ = 28138930944. Its totient is φ = 14066828160.

The previous prime is 21102220187. The next prime is 21102220231. The reversal of 21102220221 is 12202220112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21102220221 - 2²¹ = 21100123069 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21102220221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21102220231) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 291700 + ... + 356781.

It is an arithmetic number, because the mean of its divisors is an integer number (3517366368).

Almost surely, 2^21102220221 is an apocalyptic number.

It is an amenable number.

21102220221 is a deficient number, since it is larger than the sum of its proper divisors (7036710723).

21102220221 is a wasteful number, since it uses less digits than its factorization.

21102220221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 659331.

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

Adding to 21102220221 its reverse (12202220112), we get a palindrome (33304440333).

The spelling of 21102220221 in words is "twenty-one billion, one hundred two million, two hundred twenty thousand, two hundred twenty-one".