21001222202121 has 32 divisors (see below), whose sum is σ = 35756270899200. Its totient is φ = 11933655374160.

The previous prime is 21001222202111. The next prime is 21001222202123. The reversal of 21001222202121 is 12120222210012.

It is a happy number.

21001222202121 is a `hidden beast` number, since 210 + 0 + 1 + 22 + 220 + 212 + 1 = 666.

It is not a de Polignac number, because 21001222202121 - 2⁵ = 21001222202089 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21001222202094 and 21001222202103.

It is not an unprimeable number, because it can be changed into a prime (21001222202123) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 310350465 + ... + 310418126.

It is an arithmetic number, because the mean of its divisors is an integer number (1117383465600).

Almost surely, 2^{21001222202121} is an apocalyptic number.

21001222202121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21001222202121 is a deficient number, since it is larger than the sum of its proper divisors (14755048697079).

21001222202121 is a wasteful number, since it uses less digits than its factorization.

21001222202121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 620768786 (or 620768780 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21001222202121 its reverse (12120222210012), we get a palindrome (33121444412133).

The spelling of 21001222202121 in words is "twenty-one trillion, one billion, two hundred twenty-two million, two hundred two thousand, one hundred twenty-one".