21111220001 has 2 divisors, whose sum is σ = 21111220002. Its totient is φ = 21111220000.

The previous prime is 21111219949. The next prime is 21111220037. The reversal of 21111220001 is 10002211112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11114219776 + 9997000225 = 105424^2 + 99985^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111220001 - 2⁶ = 21111219937 is a prime.

It is not a weakly prime, because it can be changed into another prime (21111220061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555610000 + 10555610001.

It is an arithmetic number, because the mean of its divisors is an integer number (10555610001).

Almost surely, 2^21111220001 is an apocalyptic number.

It is an amenable number.

21111220001 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111220001 is an equidigital number, since it uses as much as digits as its factorization.

21111220001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21111220001 its reverse (10002211112), we get a palindrome (31113431113).

The spelling of 21111220001 in words is "twenty-one billion, one hundred eleven million, two hundred twenty thousand, one".