21001211121213 has 20 divisors (see below), whose sum is σ = 32137354692828. Its totient is φ = 13659324304320.

The previous prime is 21001211121211. The next prime is 21001211121229. The reversal of 21001211121213 is 31212111210012.

It is a happy number.

21001211121213 is a `hidden beast` number, since 210 + 0 + 121 + 1 + 121 + 213 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 12776492634084 + 8224718487129 = 3574422^2 + 2867877^2 .

It is not a de Polignac number, because 21001211121213 - 2¹ = 21001211121211 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001211121211) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 3161877306 + ... + 3161883947.

Almost surely, 2^{21001211121213} is an apocalyptic number.

It is an amenable number.

21001211121213 is a deficient number, since it is larger than the sum of its proper divisors (11136143571615).

21001211121213 is an equidigital number, since it uses as much as digits as its factorization.

21001211121213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6323761306 (or 6323761297 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 18.

Adding to 21001211121213 its reverse (31212111210012), we get a palindrome (52213322331225).

The spelling of 21001211121213 in words is "twenty-one trillion, one billion, two hundred eleven million, one hundred twenty-one thousand, two hundred thirteen".