21001220011001 has 2 divisors, whose sum is σ = 21001220011002. Its totient is φ = 21001220011000.

The previous prime is 21001220010977. The next prime is 21001220011033. The reversal of 21001220011001 is 10011002210012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20550817956601 + 450402054400 = 4533301^2 + 671120^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001220011001 - 2³⁴ = 20984040141817 is a prime.

It is a super-2 number, since 2×21001220011001² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21001220011601) 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, 10500610005500 + 10500610005501.

It is an arithmetic number, because the mean of its divisors is an integer number (10500610005501).

Almost surely, 2^{21001220011001} is an apocalyptic number.

It is an amenable number.

21001220011001 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001220011001 is an equidigital number, since it uses as much as digits as its factorization.

21001220011001 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 21001220011001 its reverse (10011002210012), we get a palindrome (31012222221013).

The spelling of 21001220011001 in words is "twenty-one trillion, one billion, two hundred twenty million, eleven thousand, one".