51251509 has 4 divisors (see below), whose sum is σ = 51381004. Its totient is φ = 51122016.

The previous prime is 51251491. The next prime is 51251527. The reversal of 51251509 is 90515215.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (51251491) and next prime (51251527).

It can be written as a sum of positive squares in 2 ways, for example, as 24780484 + 26471025 = 4978^2 + 5145^2 .

It is a cyclic number.

It is not a de Polignac number, because 51251509 - 2¹⁷ = 51120437 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51257509) 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 3 ways as a sum of consecutive naturals, for example, 64152 + ... + 64945.

It is an arithmetic number, because the mean of its divisors is an integer number (12845251).

Almost surely, 2^51251509 is an apocalyptic number.

It is an amenable number.

51251509 is a deficient number, since it is larger than the sum of its proper divisors (129495).

51251509 is a wasteful number, since it uses less digits than its factorization.

51251509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129494.

The product of its (nonzero) digits is 2250, while the sum is 28.

The square root of 51251509 is about 7159.0159239940. The cubic root of 51251509 is about 371.4515876622.

The spelling of 51251509 in words is "fifty-one million, two hundred fifty-one thousand, five hundred nine".