21021121211 has 4 divisors (see below), whose sum is σ = 21081354000. Its totient is φ = 20960888424.

The previous prime is 21021121201. The next prime is 21021121241. The reversal of 21021121211 is 11212112012.

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

It is a cyclic number.

It is not a de Polignac number, because 21021121211 - 2¹⁴ = 21021104827 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21021121201) 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, 30115871 + ... + 30116568.

It is an arithmetic number, because the mean of its divisors is an integer number (5270338500).

Almost surely, 2^21021121211 is an apocalyptic number.

21021121211 is a deficient number, since it is larger than the sum of its proper divisors (60232789).

21021121211 is an equidigital number, since it uses as much as digits as its factorization.

21021121211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60232788.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21021121211 its reverse (11212112012), we get a palindrome (32233233223).

The spelling of 21021121211 in words is "twenty-one billion, twenty-one million, one hundred twenty-one thousand, two hundred eleven".