51111 has 10 divisors (see below), whose sum is σ = 76472. Its totient is φ = 34020.

The previous prime is 51109. The next prime is 51131. The reversal of 51111 is 11115.

It is not a de Polignac number, because 51111 - 2¹ = 51109 is a prime.

It is a super-2 number, since 2×51111² = 5224668642, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Duffinian number.

51111 is a modest number, since divided by 111 gives 51 as remainder.

It is a plaindrome in base 14.

It is a nialpdrome in base 9 and base 10.

It is a junction number, because it is equal to n+sod(n) for n = 51093 and 51102.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51131) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 235 + ... + 396.

2⁵¹¹¹¹ is an apocalyptic number.

51111 is a deficient number, since it is larger than the sum of its proper divisors (25361).

51111 is an equidigital number, since it uses as much as digits as its factorization.

51111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 643 (or 634 counting only the distinct ones).

The product of its digits is 5, while the sum is 9.

The square root of 51111 is about 226.0774203674. The cubic root of 51111 is about 37.1111824918. Note that the first 4 decimals are identical.

Adding to 51111 its reverse (11115), we get a palindrome (62226).

It can be divided in two parts, 5 and 1111, that multiplied together give a palindrome (5555).

The spelling of 51111 in words is "fifty-one thousand, one hundred eleven".