51815810578 has 24 divisors (see below), whose sum is σ = 92618511804. Its totient is φ = 21665145600.

The previous prime is 51815810573. The next prime is 51815810587. The reversal of 51815810578 is 87501851815.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 51409667169 + 406143409 = 226737^2 + 20153^2 .

It is a Harshad number since it is a multiple of its sum of digits (49).

It is not an unprimeable number, because it can be changed into a prime (51815810573) 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 11 ways as a sum of consecutive naturals, for example, 6443943 + ... + 6451978.

Almost surely, 2^51815810578 is an apocalyptic number.

51815810578 is a deficient number, since it is larger than the sum of its proper divisors (40802701226).

51815810578 is a wasteful number, since it uses less digits than its factorization.

51815810578 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12895978 (or 12895971 counting only the distinct ones).

The product of its (nonzero) digits is 448000, while the sum is 49.

The spelling of 51815810578 in words is "fifty-one billion, eight hundred fifteen million, eight hundred ten thousand, five hundred seventy-eight".