21201221202021 has 96 divisors (see below), whose sum is σ = 36154827042048. Its totient is φ = 11718753822720.

The previous prime is 21201221202013. The next prime is 21201221202043. The reversal of 21201221202021 is 12020212210212.

It is a happy number.

21201221202021 is a `hidden beast` number, since 21 + 201 + 221 + 20 + 202 + 1 = 666.

It is not a de Polignac number, because 21201221202021 - 2³ = 21201221202013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21201221201985 and 21201221202003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201221201021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 624963766 + ... + 624997688.

It is an arithmetic number, because the mean of its divisors is an integer number (376612781688).

Almost surely, 2^{21201221202021} is an apocalyptic number.

21201221202021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21201221202021 is a deficient number, since it is larger than the sum of its proper divisors (14953605840027).

21201221202021 is a wasteful number, since it uses less digits than its factorization.

21201221202021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35531 (or 35528 counting only the distinct ones).

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

Adding to 21201221202021 its reverse (12020212210212), we get a palindrome (33221433412233).

The spelling of 21201221202021 in words is "twenty-one trillion, two hundred one billion, two hundred twenty-one million, two hundred two thousand, twenty-one".