51239209 has 16 divisors (see below), whose sum is σ = 59913216. Its totient is φ = 42915600.

The previous prime is 51239203. The next prime is 51239231. The reversal of 51239209 is 90293215.

51239209 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 51239209 - 2¹⁹ = 50714921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51239203) 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, 64714 + ... + 65500.

It is an arithmetic number, because the mean of its divisors is an integer number (3744576).

Almost surely, 2^51239209 is an apocalyptic number.

It is an amenable number.

51239209 is a deficient number, since it is larger than the sum of its proper divisors (8674007).

51239209 is a wasteful number, since it uses less digits than its factorization.

51239209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 996.

The product of its (nonzero) digits is 4860, while the sum is 31.

The square root of 51239209 is about 7158.1568158291. The cubic root of 51239209 is about 371.4218700327.

The spelling of 51239209 in words is "fifty-one million, two hundred thirty-nine thousand, two hundred nine".