21011101221001 has 4 divisors (see below), whose sum is σ = 21024159706900. Its totient is φ = 20998042735104.

The previous prime is 21011101220899. The next prime is 21011101221043. The reversal of 21011101221001 is 10012210111012.

It is a happy number.

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 19511443814976 + 1499657406025 = 4417176^2 + 1224605^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011101221001 - 2⁷ = 21011101220873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21011101221401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6529240536 + ... + 6529243753.

It is an arithmetic number, because the mean of its divisors is an integer number (5256039926725).

Almost surely, 2^{21011101221001} is an apocalyptic number.

It is an amenable number.

21011101221001 is a deficient number, since it is larger than the sum of its proper divisors (13058485899).

21011101221001 is a wasteful number, since it uses less digits than its factorization.

21011101221001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13058485898.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21011101221001 its reverse (10012210111012), we get a palindrome (31023311332013).

The spelling of 21011101221001 in words is "twenty-one trillion, eleven billion, one hundred one million, two hundred twenty-one thousand, one".