51540809 has 4 divisors (see below), whose sum is σ = 51723216. Its totient is φ = 51358404.

The previous prime is 51540803. The next prime is 51540833. The reversal of 51540809 is 90804515.

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.

It is a cyclic number.

It is not a de Polignac number, because 51540809 - 2¹⁶ = 51475273 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 (51540803) 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, 90779 + ... + 91344.

It is an arithmetic number, because the mean of its divisors is an integer number (12930804).

Almost surely, 2^51540809 is an apocalyptic number.

It is an amenable number.

51540809 is a deficient number, since it is larger than the sum of its proper divisors (182407).

51540809 is a wasteful number, since it uses less digits than its factorization.

51540809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182406.

The product of its (nonzero) digits is 7200, while the sum is 32.

The square root of 51540809 is about 7179.1927819219. The cubic root of 51540809 is about 372.1491891101.

The spelling of 51540809 in words is "fifty-one million, five hundred forty thousand, eight hundred nine".