21001111001201 has 4 divisors (see below), whose sum is σ = 21001162200804. Its totient is φ = 21001059801600.

The previous prime is 21001111001113. The next prime is 21001111001207. The reversal of 21001111001201 is 10210011110012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11772584454400 + 9228526546801 = 3431120^2 + 3037849^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21001111001201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21001111001207) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24979520 + ... + 25806561.

It is an arithmetic number, because the mean of its divisors is an integer number (5250290550201).

Almost surely, 2^{21001111001201} is an apocalyptic number.

It is an amenable number.

21001111001201 is a deficient number, since it is larger than the sum of its proper divisors (51199603).

21001111001201 is an equidigital number, since it uses as much as digits as its factorization.

21001111001201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51199602.

The product of its (nonzero) digits is 4, while the sum is 11.

Adding to 21001111001201 its reverse (10210011110012), we get a palindrome (31211122111213).

The spelling of 21001111001201 in words is "twenty-one trillion, one billion, one hundred eleven million, one thousand, two hundred one".