51665439 has 16 divisors (see below), whose sum is σ = 79511040. Its totient is φ = 29229600.

The previous prime is 51665423. The next prime is 51665461. The reversal of 51665439 is 93456615.

51665439 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 51665439 - 2⁴ = 51665423 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 51665397 and 51665406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51665039) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10059 + ... + 14300.

It is an arithmetic number, because the mean of its divisors is an integer number (4969440).

Almost surely, 2^51665439 is an apocalyptic number.

51665439 is a deficient number, since it is larger than the sum of its proper divisors (27845601).

51665439 is a wasteful number, since it uses less digits than its factorization.

51665439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24470.

The product of its digits is 97200, while the sum is 39.

The square root of 51665439 is about 7187.8674862577. The cubic root of 51665439 is about 372.4489103092.

The spelling of 51665439 in words is "fifty-one million, six hundred sixty-five thousand, four hundred thirty-nine".