20001021211001 has 2 divisors, whose sum is σ = 20001021211002. Its totient is φ = 20001021211000.

The previous prime is 20001021210991. The next prime is 20001021211013. The reversal of 20001021211001 is 10011212010002.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17092891266025 + 2908129944976 = 4134355^2 + 1705324^2 .

It is a cyclic number.

It is not a de Polignac number, because 20001021211001 - 2²² = 20001017016697 is a prime.

It is not a weakly prime, because it can be changed into another prime (20001021211021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10000510605500 + 10000510605501.

It is an arithmetic number, because the mean of its divisors is an integer number (10000510605501).

Almost surely, 2^{20001021211001} is an apocalyptic number.

It is an amenable number.

20001021211001 is a deficient number, since it is larger than the sum of its proper divisors (1).

20001021211001 is an equidigital number, since it uses as much as digits as its factorization.

20001021211001 is an evil number, because the sum of its binary digits is even.

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

Adding to 20001021211001 its reverse (10011212010002), we get a palindrome (30012233221003).

The spelling of 20001021211001 in words is "twenty trillion, one billion, twenty-one million, two hundred eleven thousand, one".