51123581 has 4 divisors (see below), whose sum is σ = 51138912. Its totient is φ = 51108252.

The previous prime is 51123511. The next prime is 51123599. The reversal of 51123581 is 18532115.

It is a happy number.

51123581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 51123581 - 2²² = 46929277 is a prime.

It is a super-2 number, since 2×51123581² = 5227241068527122, 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 51123581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51123511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 311 + ... + 10116.

It is an arithmetic number, because the mean of its divisors is an integer number (12784728).

Almost surely, 2^51123581 is an apocalyptic number.

It is an amenable number.

51123581 is a deficient number, since it is larger than the sum of its proper divisors (15331).

51123581 is a wasteful number, since it uses less digits than its factorization.

51123581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15330.

The product of its digits is 1200, while the sum is 26.

The square root of 51123581 is about 7150.0755940060. The cubic root of 51123581 is about 371.1422722117.

Adding to 51123581 its reverse (18532115), we get a palindrome (69655696).

The spelling of 51123581 in words is "fifty-one million, one hundred twenty-three thousand, five hundred eighty-one".