20111 has 12 divisors (see below), whose sum is σ = 26352. Its totient is φ = 14976.

The previous prime is 20107. The next prime is 20113. The reversal of 20111 is 11102.

20111 = T₄₉ + T₅₀ + ... + T₆₁.

It is a happy number.

20111 is nontrivially palindromic in base 12.

It is not a de Polignac number, because 20111 - 2² = 20107 is a prime.

It is a Duffinian number.

20111 is a modest number, since divided by 111 gives 20 as remainder.

It is a nialpdrome in base 13.

It is a junction number, because it is equal to n+sod(n) for n = 20095 and 20104.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20113) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1175 + ... + 1191.

It is an arithmetic number, because the mean of its divisors is an integer number (2196).

2²⁰¹¹¹ is an apocalyptic number.

20111 is a deficient number, since it is larger than the sum of its proper divisors (6241).

20111 is a wasteful number, since it uses less digits than its factorization.

20111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50 (or 37 counting only the distinct ones).

The product of its (nonzero) digits is 2, while the sum is 5.

The square root of 20111 is about 141.8132574903. The cubic root of 20111 is about 27.1943002763.

Adding to 20111 its reverse (11102), we get a palindrome (31213).

Subtracting from 20111 its reverse (11102), we obtain a palindrome (9009).

Multiplying 20111 by its reverse (11102), we get a palindrome (223272322).

It can be divided in two parts, 201 and 11, that multiplied together give a triangular number (2211 = T₆₆).

The spelling of 20111 in words is "twenty thousand, one hundred eleven", and thus it is an iban number.