51566581 has 4 divisors (see below), whose sum is σ = 56254464. Its totient is φ = 46878700.

The previous prime is 51566579. The next prime is 51566587. The reversal of 51566581 is 18566515.

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 not a de Polignac number, because 51566581 - 2¹ = 51566579 is a prime.

It is a super-2 number, since 2×51566581² = 5318224552059122, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 51566581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51566587) 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, 2343925 + ... + 2343946.

It is an arithmetic number, because the mean of its divisors is an integer number (14063616).

Almost surely, 2^51566581 is an apocalyptic number.

It is an amenable number.

51566581 is a deficient number, since it is larger than the sum of its proper divisors (4687883).

51566581 is a wasteful number, since it uses less digits than its factorization.

51566581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4687882.

The product of its digits is 36000, while the sum is 37.

The square root of 51566581 is about 7180.9874669157. The cubic root of 51566581 is about 372.2112074791.

The spelling of 51566581 in words is "fifty-one million, five hundred sixty-six thousand, five hundred eighty-one".