21112211 has 4 divisors (see below), whose sum is σ = 22223400. Its totient is φ = 20001024.

The previous prime is 21112207. The next prime is 21112241. The reversal of 21112211 is 11221112.

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 21112211 - 2² = 21112207 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21112192 and 21112201.

It is not an unprimeable number, because it can be changed into a prime (21112241) 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, 555566 + ... + 555603.

It is an arithmetic number, because the mean of its divisors is an integer number (5555850).

Almost surely, 2^21112211 is an apocalyptic number.

21112211 is a deficient number, since it is larger than the sum of its proper divisors (1111189).

21112211 is a wasteful number, since it uses less digits than its factorization.

21112211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1111188.

The product of its digits is 8, while the sum is 11.

The square root of 21112211 is about 4594.8026072945. The cubic root of 21112211 is about 276.3829444121.

Adding to 21112211 its reverse (11221112), we get a palindrome (32333323).

The spelling of 21112211 in words is "twenty-one million, one hundred twelve thousand, two hundred eleven".