21111311 has 6 divisors (see below), whose sum is σ = 22860360. Its totient is φ = 19487208.

The previous prime is 21111301. The next prime is 21111373. The reversal of 21111311 is 11311112.

It is a happy number.

It is not a de Polignac number, because 21111311 - 2⁶ = 21111247 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21111292 and 21111301.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111301) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 62291 + ... + 62628.

It is an arithmetic number, because the mean of its divisors is an integer number (3810060).

Almost surely, 2^21111311 is an apocalyptic number.

21111311 is a deficient number, since it is larger than the sum of its proper divisors (1749049).

21111311 is a wasteful number, since it uses less digits than its factorization.

21111311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124945 (or 124932 counting only the distinct ones).

The product of its digits is 6, while the sum is 11.

The square root of 21111311 is about 4594.7046695082. The cubic root of 21111311 is about 276.3790170138.

Adding to 21111311 its reverse (11311112), we get a palindrome (32422423).

The spelling of 21111311 in words is "twenty-one million, one hundred eleven thousand, three hundred eleven".