51209439 has 16 divisors (see below), whose sum is σ = 69754464. Its totient is φ = 33408000.

The previous prime is 51209401. The next prime is 51209467. The reversal of 51209439 is 93490215.

It is not a de Polignac number, because 51209439 - 2⁷ = 51209311 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51209539) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42039 + ... + 43239.

It is an arithmetic number, because the mean of its divisors is an integer number (4359654).

Almost surely, 2^51209439 is an apocalyptic number.

51209439 is a deficient number, since it is larger than the sum of its proper divisors (18545025).

51209439 is a wasteful number, since it uses less digits than its factorization.

51209439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1498.

The product of its (nonzero) digits is 9720, while the sum is 33.

The square root of 51209439 is about 7156.0770677795. The cubic root of 51209439 is about 371.3499240145.

The spelling of 51209439 in words is "fifty-one million, two hundred nine thousand, four hundred thirty-nine".