21212222201 has 2 divisors, whose sum is σ = 21212222202. Its totient is φ = 21212222200.

The previous prime is 21212222197. The next prime is 21212222233. The reversal of 21212222201 is 10222221212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12611514601 + 8600707600 = 112301^2 + 92740^2 .

It is a cyclic number.

It is not a de Polignac number, because 21212222201 - 2² = 21212222197 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21212222201.

It is not a weakly prime, because it can be changed into another prime (21212222261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606111100 + 10606111101.

It is an arithmetic number, because the mean of its divisors is an integer number (10606111101).

Almost surely, 2^21212222201 is an apocalyptic number.

It is an amenable number.

21212222201 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212222201 is an equidigital number, since it uses as much as digits as its factorization.

21212222201 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21212222201 its reverse (10222221212), we get a palindrome (31434443413).

The spelling of 21212222201 in words is "twenty-one billion, two hundred twelve million, two hundred twenty-two thousand, two hundred one".