51509729 has 8 divisors (see below), whose sum is σ = 52245000. Its totient is φ = 50778112.

The previous prime is 51509699. The next prime is 51509737. The reversal of 51509729 is 92790515.

It can be written as a sum of positive squares in 4 ways, for example, as 9778129 + 41731600 = 3127^2 + 6460^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51509729 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 51509692 and 51509701.

It is not an unprimeable number, because it can be changed into a prime (51509789) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39317 + ... + 40605.

It is an arithmetic number, because the mean of its divisors is an integer number (6530625).

Almost surely, 2^51509729 is an apocalyptic number.

It is an amenable number.

51509729 is a deficient number, since it is larger than the sum of its proper divisors (735271).

51509729 is a wasteful number, since it uses less digits than its factorization.

51509729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1827.

The product of its (nonzero) digits is 28350, while the sum is 38.

The square root of 51509729 is about 7177.0278667426. The cubic root of 51509729 is about 372.0743699347.

The spelling of 51509729 in words is "fifty-one million, five hundred nine thousand, seven hundred twenty-nine".