21011221211 has 8 divisors (see below), whose sum is σ = 21978368160. Its totient is φ = 20048542272.

The previous prime is 21011221181. The next prime is 21011221223. The reversal of 21011221211 is 11212211012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21011221211 - 2¹⁴ = 21011204827 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21011221291) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1107380 + ... + 1126193.

It is an arithmetic number, because the mean of its divisors is an integer number (2747296020).

Almost surely, 2^21011221211 is an apocalyptic number.

21011221211 is a deficient number, since it is larger than the sum of its proper divisors (967146949).

21011221211 is a wasteful number, since it uses less digits than its factorization.

21011221211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2234005.

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

Adding to 21011221211 its reverse (11212211012), we get a palindrome (32223432223).

The spelling of 21011221211 in words is "twenty-one billion, eleven million, two hundred twenty-one thousand, two hundred eleven".