51639 has 8 divisors (see below), whose sum is σ = 78720. Its totient is φ = 29496.

The previous prime is 51637. The next prime is 51647. The reversal of 51639 is 93615.

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

It is not a de Polignac number, because 51639 - 2¹ = 51637 is a prime.

It is a plaindrome in base 8.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51631) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1209 + ... + 1250.

It is an arithmetic number, because the mean of its divisors is an integer number (9840).

2⁵¹⁶³⁹ is an apocalyptic number.

51639 is a deficient number, since it is larger than the sum of its proper divisors (27081).

51639 is a wasteful number, since it uses less digits than its factorization.

51639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2469.

The product of its digits is 810, while the sum is 24.

The square root of 51639 is about 227.2421615810. The cubic root of 51639 is about 37.2385367787.

Subtracting from 51639 its sum of digits (24), we obtain a palindrome (51615).

It can be divided in two parts, 516 and 39, that added together give a palindrome (555).

The spelling of 51639 in words is "fifty-one thousand, six hundred thirty-nine".