21010011221 has 16 divisors (see below), whose sum is σ = 22570368768. Its totient is φ = 19485984000.

The previous prime is 21010011203. The next prime is 21010011223. The reversal of 21010011221 is 12211001012.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21010011221 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 (21010011223) 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, 3923696 + ... + 3929046.

It is an arithmetic number, because the mean of its divisors is an integer number (1410648048).

Almost surely, 2^21010011221 is an apocalyptic number.

It is an amenable number.

21010011221 is a deficient number, since it is larger than the sum of its proper divisors (1560357547).

21010011221 is a wasteful number, since it uses less digits than its factorization.

21010011221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8692.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21010011221 its reverse (12211001012), we get a palindrome (33221012233).

The spelling of 21010011221 in words is "twenty-one billion, ten million, eleven thousand, two hundred twenty-one".