21111212201 has 2 divisors, whose sum is σ = 21111212202. Its totient is φ = 21111212200.

The previous prime is 21111212197. The next prime is 21111212219. The reversal of 21111212201 is 10221211112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20263237801 + 847974400 = 142349^2 + 29120^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111212201 - 2² = 21111212197 is a prime.

It is not a weakly prime, because it can be changed into another prime (21111215201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555606100 + 10555606101.

It is an arithmetic number, because the mean of its divisors is an integer number (10555606101).

Almost surely, 2^21111212201 is an apocalyptic number.

It is an amenable number.

21111212201 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111212201 is an equidigital number, since it uses as much as digits as its factorization.

21111212201 is an evil number, because the sum of its binary digits is even.

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

Adding to 21111212201 its reverse (10221211112), we get a palindrome (31332423313).

The spelling of 21111212201 in words is "twenty-one billion, one hundred eleven million, two hundred twelve thousand, two hundred one".