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21211211 = 719915227

21211211 has 8 divisors (see below), whose sum is σ = 24364800. Its totient is φ = 18088488.

The previous prime is 21211181. The next prime is 21211217. The reversal of 21211211 is 11211212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2k-21211211 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21211192 and 21211201.

It is not an unprimeable number, because it can be changed into a prime (21211217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6221 + ... + 9006.

It is an arithmetic number, because the mean of its divisors is an integer number (3045600).

Almost surely, 221211211 is an apocalyptic number.

21211211 is a deficient number, since it is larger than the sum of its proper divisors (3153589).

21211211 is a wasteful number, since it uses less digits than its factorization.

21211211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15433.

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

The square root of 21211211 is about 4605.5630491830. The cubic root of 21211211 is about 276.8142785786.

Adding to 21211211 its reverse (11211212), we get a palindrome (32422423).

Subtracting from 21211211 its reverse (11211212), we obtain a palindrome (9999999).

It can be divided in two parts, 212 and 11211, that multiplied together give a palindrome (2376732).

The spelling of 21211211 in words is "twenty-one million, two hundred eleven thousand, two hundred eleven".

Divisors: 1 7 199 1393 15227 106589 3030173 21211211