51815500 has 48 divisors (see below), whose sum is σ = 123465888. Its totient is φ = 18840000.

The previous prime is 51815497. The next prime is 51815501. The reversal of 51815500 is 551815.

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is not an unprimeable number, because it can be changed into a prime (51815501) 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 15 ways as a sum of consecutive naturals, for example, 790 + ... + 10210.

It is an arithmetic number, because the mean of its divisors is an integer number (2572206).

Almost surely, 2^51815500 is an apocalyptic number.

51815500 is a gapful number since it is divisible by the number (50) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51815500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (61732944).

51815500 is an abundant number, since it is smaller than the sum of its proper divisors (71650388).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51815500 is a wasteful number, since it uses less digits than its factorization.

51815500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9451 (or 9439 counting only the distinct ones).

The product of its (nonzero) digits is 1000, while the sum is 25.

The square root of 51815500 is about 7198.2984100411. The cubic root of 51815500 is about 372.8091513377.

The spelling of 51815500 in words is "fifty-one million, eight hundred fifteen thousand, five hundred".