21002211121 has 4 divisors (see below), whose sum is σ = 21016002672. Its totient is φ = 20988419572.

The previous prime is 21002211119. The next prime is 21002211143. The reversal of 21002211121 is 12111220012.

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 21002211121 - 2¹ = 21002211119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21002211151) 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, 6893491 + ... + 6896536.

It is an arithmetic number, because the mean of its divisors is an integer number (5254000668).

Almost surely, 2^21002211121 is an apocalyptic number.

It is an amenable number.

21002211121 is a deficient number, since it is larger than the sum of its proper divisors (13791551).

21002211121 is a wasteful number, since it uses less digits than its factorization.

21002211121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13791550.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21002211121 its reverse (12111220012), we get a palindrome (33113431133).

The spelling of 21002211121 in words is "twenty-one billion, two million, two hundred eleven thousand, one hundred twenty-one".