21001111121201 has 4 divisors (see below), whose sum is σ = 21001123264752. Its totient is φ = 21001098977652.

The previous prime is 21001111121149. The next prime is 21001111121203. The reversal of 21001111121201 is 10212111110012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21001111121201 - 2¹⁰ = 21001111120177 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21001111121203) 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, 2938811 + ... + 7116096.

It is an arithmetic number, because the mean of its divisors is an integer number (5250280816188).

Almost surely, 2^{21001111121201} is an apocalyptic number.

It is an amenable number.

21001111121201 is a deficient number, since it is larger than the sum of its proper divisors (12143551).

21001111121201 is a wasteful number, since it uses less digits than its factorization.

21001111121201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12143550.

The product of its (nonzero) digits is 8, while the sum is 14.

Adding to 21001111121201 its reverse (10212111110012), we get a palindrome (31213222231213).

The spelling of 21001111121201 in words is "twenty-one trillion, one billion, one hundred eleven million, one hundred twenty-one thousand, two hundred one".