51115520 has 80 divisors (see below), whose sum is σ = 125804448. Its totient is φ = 19906560.

The previous prime is 51115513. The next prime is 51115523. The reversal of 51115520 is 2551115.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-3 number, since 3×51115520³ (a number of 24 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 51115492 and 51115501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51115523) 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, 104717 + ... + 105203.

Almost surely, 2^51115520 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51115520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (62902224).

51115520 is an abundant number, since it is smaller than the sum of its proper divisors (74688928).

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

51115520 is an equidigital number, since it uses as much as digits as its factorization.

51115520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 551 (or 535 counting only the distinct ones).

The product of its (nonzero) digits is 250, while the sum is 20.

The square root of 51115520 is about 7149.5118714497. The cubic root of 51115520 is about 371.1227643508.

Adding to 51115520 its reverse (2551115), we get a palindrome (53666635).

The spelling of 51115520 in words is "fifty-one million, one hundred fifteen thousand, five hundred twenty".