51218 has 4 divisors (see below), whose sum is σ = 76830. Its totient is φ = 25608.

The previous prime is 51217. The next prime is 51229. The reversal of 51218 is 81215.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 26569 + 24649 = 163^2 + 157^2 .

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 51196 and 51205.

It is not an unprimeable number, because it can be changed into a prime (51217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12803 + ... + 12806.

2⁵¹²¹⁸ is an apocalyptic number.

51218 is a deficient number, since it is larger than the sum of its proper divisors (25612).

51218 is a wasteful number, since it uses less digits than its factorization.

51218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25611.

The product of its digits is 80, while the sum is 17.

The square root of 51218 is about 226.3139412409. The cubic root of 51218 is about 37.1370616486.

It can be divided in two parts, 512 and 18, that multiplied together give a square (9216 = 96²).

The spelling of 51218 in words is "fifty-one thousand, two hundred eighteen".