21221221210001 has 2 divisors, whose sum is σ = 21221221210002. Its totient is φ = 21221221210000.

The previous prime is 21221221209973. The next prime is 21221221210031. The reversal of 21221221210001 is 10001212212212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21077143270225 + 144077939776 = 4590985^2 + 379576^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221221210001 - 2²² = 21221217015697 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21221221210031) 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 as a sum of consecutive naturals, namely, 10610610605000 + 10610610605001.

It is an arithmetic number, because the mean of its divisors is an integer number (10610610605001).

Almost surely, 2^{21221221210001} is an apocalyptic number.

It is an amenable number.

21221221210001 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221221210001 is an equidigital number, since it uses as much as digits as its factorization.

21221221210001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21221221210001 its reverse (10001212212212), we get a palindrome (31222433422213).

It can be divided in two parts, 212212212 and 10001, that multiplied together give a palindrome (2122334332212).

The spelling of 21221221210001 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred twenty-one million, two hundred ten thousand, one".