21211211101111 has 4 divisors (see below), whose sum is σ = 21299224425424. Its totient is φ = 21123197776800.

The previous prime is 21211211101081. The next prime is 21211211101181. The reversal of 21211211101111 is 11110111211212.

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 21211211101111 - 2⁷ = 21211211100983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211211101181) 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, 44006661795 + ... + 44006662276.

It is an arithmetic number, because the mean of its divisors is an integer number (5324806106356).

Almost surely, 2^{21211211101111} is an apocalyptic number.

21211211101111 is a deficient number, since it is larger than the sum of its proper divisors (88013324313).

21211211101111 is an equidigital number, since it uses as much as digits as its factorization.

21211211101111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88013324312.

The product of its (nonzero) digits is 8, while the sum is 16.

Adding to 21211211101111 its reverse (11110111211212), we get a palindrome (32321322312323).

It can be divided in two parts, 21211211101 and 111, that added together give a palindrome (21211211212).

The spelling of 21211211101111 in words is "twenty-one trillion, two hundred eleven billion, two hundred eleven million, one hundred one thousand, one hundred eleven".