21001101019901 has 2 divisors, whose sum is σ = 21001101019902. Its totient is φ = 21001101019900.

The previous prime is 21001101019859. The next prime is 21001101020033. The reversal of 21001101019901 is 10991010110012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20176500814276 + 824600205625 = 4491826^2 + 908075^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001101019901 - 2²⁶ = 21001033911037 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21001101019001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500550509950 + 10500550509951.

It is an arithmetic number, because the mean of its divisors is an integer number (10500550509951).

Almost surely, 2^{21001101019901} is an apocalyptic number.

It is an amenable number.

21001101019901 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001101019901 is an equidigital number, since it uses as much as digits as its factorization.

21001101019901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 162, while the sum is 26.

Adding to 21001101019901 its reverse (10991010110012), we get a palindrome (31992111129913).

The spelling of 21001101019901 in words is "twenty-one trillion, one billion, one hundred one million, nineteen thousand, nine hundred one".