51649865 has 8 divisors (see below), whose sum is σ = 62582208. Its totient is φ = 40918320.

The previous prime is 51649823. The next prime is 51649867. The reversal of 51649865 is 56894615.

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

It is not a de Polignac number, because 51649865 - 2¹⁰ = 51648841 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (51649867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49631 + ... + 50660.

It is an arithmetic number, because the mean of its divisors is an integer number (7822776).

Almost surely, 2^51649865 is an apocalyptic number.

It is an amenable number.

51649865 is a deficient number, since it is larger than the sum of its proper divisors (10932343).

51649865 is a wasteful number, since it uses less digits than its factorization.

51649865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100399.

The product of its digits is 259200, while the sum is 44.

The square root of 51649865 is about 7186.7840512986. The cubic root of 51649865 is about 372.4114829537.

The spelling of 51649865 in words is "fifty-one million, six hundred forty-nine thousand, eight hundred sixty-five".