21001210012221 has 16 divisors (see below), whose sum is σ = 29066371061760. Its totient is φ = 13473474064560.

The previous prime is 21001210012187. The next prime is 21001210012253. The reversal of 21001210012221 is 12221001210012.

It is not a de Polignac number, because 21001210012221 - 2⁶ = 21001210012157 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21001210012221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001210012271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 630763975 + ... + 630797268.

It is an arithmetic number, because the mean of its divisors is an integer number (1816648191360).

Almost surely, 2^{21001210012221} is an apocalyptic number.

It is an amenable number.

21001210012221 is a deficient number, since it is larger than the sum of its proper divisors (8065161049539).

21001210012221 is a wasteful number, since it uses less digits than its factorization.

21001210012221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1261561456.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21001210012221 its reverse (12221001210012), we get a palindrome (33222211222233).

The spelling of 21001210012221 in words is "twenty-one trillion, one billion, two hundred ten million, twelve thousand, two hundred twenty-one".