51818181 has 8 divisors (see below), whose sum is σ = 69346944. Its totient is φ = 34417440.

The previous prime is 51818161. The next prime is 51818183. The reversal of 51818181 is 18181815.

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

It is not a de Polignac number, because 51818181 - 2¹⁷ = 51687109 is a prime.

It is a super-2 number, since 2×51818181² = 5370247764297522, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51818183) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31056 + ... + 32681.

It is an arithmetic number, because the mean of its divisors is an integer number (8668368).

Almost surely, 2^51818181 is an apocalyptic number.

It is an amenable number.

51818181 is a deficient number, since it is larger than the sum of its proper divisors (17528763).

51818181 is a wasteful number, since it uses less digits than its factorization.

51818181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64011.

The product of its digits is 2560, while the sum is 33.

The square root of 51818181 is about 7198.4846321986. The cubic root of 51818181 is about 372.8155811003.

Adding to 51818181 its reverse (18181815), we get a palindrome (69999996).

The spelling of 51818181 in words is "fifty-one million, eight hundred eighteen thousand, one hundred eighty-one".