51805947 has 4 divisors (see below), whose sum is σ = 69074600. Its totient is φ = 34537296.

The previous prime is 51805939. The next prime is 51805961. The reversal of 51805947 is 74950815.

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

It is not a de Polignac number, because 51805947 - 2³ = 51805939 is a prime.

It is a super-2 number, since 2×51805947² = 5367712289133618, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51805997) 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, 8634322 + ... + 8634327.

It is an arithmetic number, because the mean of its divisors is an integer number (17268650).

Almost surely, 2^51805947 is an apocalyptic number.

51805947 is a deficient number, since it is larger than the sum of its proper divisors (17268653).

51805947 is a wasteful number, since it uses less digits than its factorization.

51805947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17268652.

The product of its (nonzero) digits is 50400, while the sum is 39.

The square root of 51805947 is about 7197.6348198558. The cubic root of 51805947 is about 372.7862388584.

The spelling of 51805947 in words is "fifty-one million, eight hundred five thousand, nine hundred forty-seven".