51439 has 2 divisors, whose sum is σ = 51440.
Its totient is φ = 51438.
The previous prime is 51437. The next prime is 51449. The reversal of 51439 is 93415.
It is a weak prime.
It is a cyclic number.
It is not a de Polignac number, because 51439 - 21 = 51437 is a prime.
Together with 51437, it forms a pair of twin primes.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (51431) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25719 + 25720.
It is an arithmetic number, because the mean of its divisors is an integer number (25720).
251439 is an apocalyptic number.
51439 is a deficient number, since it is larger than the sum of its proper divisors (1).
51439 is an equidigital number, since it uses as much as digits as its factorization.
51439 is an evil number, because the sum of its binary digits is even.
The product of its digits is 540, while the sum is 22.
The square root of 51439 is about 226.8016754788.
The cubic root of 51439 is about 37.1903991102.
It can be divided in two parts, 5 and 1439, that added together give a square (1444 = 382).
The spelling of 51439 in words is "fifty-one thousand, four hundred thirty-nine".