21220101122221 has 16 divisors (see below), whose sum is σ = 21677417452080. Its totient is φ = 20764900316160.

The previous prime is 21220101122183. The next prime is 21220101122237. The reversal of 21220101122221 is 12222110102212.

It can be written as a sum of positive squares in 8 ways, for example, as 3860262210025 + 17359838912196 = 1964755^2 + 4166514^2 .

It is a cyclic number.

It is not a de Polignac number, because 21220101122221 - 2¹⁷ = 21220100991149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220101152221) 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, 601442101 + ... + 601477381.

It is an arithmetic number, because the mean of its divisors is an integer number (1354838590755).

Almost surely, 2^{21220101122221} is an apocalyptic number.

It is an amenable number.

21220101122221 is a deficient number, since it is larger than the sum of its proper divisors (457316329859).

21220101122221 is a wasteful number, since it uses less digits than its factorization.

21220101122221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64896.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21220101122221 its reverse (12222110102212), we get a palindrome (33442211224433).

The spelling of 21220101122221 in words is "twenty-one trillion, two hundred twenty billion, one hundred one million, one hundred twenty-two thousand, two hundred twenty-one".