51515220 has 48 divisors (see below), whose sum is σ = 144563328. Its totient is φ = 13706880.

The previous prime is 51515209. The next prime is 51515221. The reversal of 51515220 is 2251515.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51515221) 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, 43030 + ... + 44210.

It is an arithmetic number, because the mean of its divisors is an integer number (3011736).

Almost surely, 2^51515220 is an apocalyptic number.

It is an amenable number.

51515220 is an abundant number, since it is smaller than the sum of its proper divisors (93048108).

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

51515220 is a wasteful number, since it uses less digits than its factorization.

51515220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1920 (or 1918 counting only the distinct ones).

The product of its (nonzero) digits is 500, while the sum is 21.

The square root of 51515220 is about 7177.4103965149. The cubic root of 51515220 is about 372.0875906589.

Adding to 51515220 its reverse (2251515), we get a palindrome (53766735).

The spelling of 51515220 in words is "fifty-one million, five hundred fifteen thousand, two hundred twenty".