21102001011221 has 24 divisors (see below), whose sum is σ = 23000926122504. Its totient is φ = 19350250583040.

The previous prime is 21102001011199. The next prime is 21102001011257. The reversal of 21102001011221 is 12211010020112.

It can be written as a sum of positive squares in 12 ways, for example, as 13836205287025 + 7265795724196 = 3719705^2 + 2695514^2 .

It is not a de Polignac number, because 21102001011221 - 2⁴² = 16703954500117 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21102001011196 and 21102001011205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21102001011521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 118168361 + ... + 118346801.

It is an arithmetic number, because the mean of its divisors is an integer number (958371921771).

Almost surely, 2^{21102001011221} is an apocalyptic number.

It is an amenable number.

21102001011221 is a deficient number, since it is larger than the sum of its proper divisors (1898925111283).

21102001011221 is a wasteful number, since it uses less digits than its factorization.

21102001011221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 183081 (or 183068 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21102001011221 its reverse (12211010020112), we get a palindrome (33313011031333).

The spelling of 21102001011221 in words is "twenty-one trillion, one hundred two billion, one million, eleven thousand, two hundred twenty-one".