51125909 has 4 divisors (see below), whose sum is σ = 51146304. Its totient is φ = 51105516.

The previous prime is 51125861. The next prime is 51125911. The reversal of 51125909 is 90952115.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 90952115 = 5 ⋅18190423.

It is a cyclic number.

It is not a de Polignac number, because 51125909 - 2²⁰ = 50077333 is a prime.

It is a super-2 number, since 2×51125909² = 5227717142152562, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51125959) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5807 + ... + 11660.

It is an arithmetic number, because the mean of its divisors is an integer number (12786576).

Almost surely, 2^51125909 is an apocalyptic number.

It is an amenable number.

51125909 is a deficient number, since it is larger than the sum of its proper divisors (20395).

51125909 is a wasteful number, since it uses less digits than its factorization.

51125909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20394.

The product of its (nonzero) digits is 4050, while the sum is 32.

The square root of 51125909 is about 7150.2383876344. The cubic root of 51125909 is about 371.1479056596.

The spelling of 51125909 in words is "fifty-one million, one hundred twenty-five thousand, nine hundred nine".