51218581 has 8 divisors (see below), whose sum is σ = 51937760. Its totient is φ = 50504688.

The previous prime is 51218561. The next prime is 51218593. The reversal of 51218581 is 18581215.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 51218581 - 2²³ = 42829973 is a prime.

It is a super-2 number, since 2×51218581² = 5246686079307122, 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 (51218551) 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 7 ways as a sum of consecutive naturals, for example, 20650 + ... + 22996.

It is an arithmetic number, because the mean of its divisors is an integer number (6492220).

Almost surely, 2^51218581 is an apocalyptic number.

It is an amenable number.

51218581 is a deficient number, since it is larger than the sum of its proper divisors (719179).

51218581 is a wasteful number, since it uses less digits than its factorization.

51218581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2643.

The product of its digits is 3200, while the sum is 31.

The square root of 51218581 is about 7156.7157970678. The cubic root of 51218581 is about 371.3720207156.

Adding to 51218581 its reverse (18581215), we get a palindrome (69799796).

The spelling of 51218581 in words is "fifty-one million, two hundred eighteen thousand, five hundred eighty-one".