51515920 has 20 divisors (see below), whose sum is σ = 119774700. Its totient is φ = 20606336.

The previous prime is 51515869. The next prime is 51515923. The reversal of 51515920 is 2951515.

It can be written as a sum of positive squares in 2 ways, for example, as 14500864 + 37015056 = 3808^2 + 6084^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is not an unprimeable number, because it can be changed into a prime (51515923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 321895 + ... + 322054.

It is an arithmetic number, because the mean of its divisors is an integer number (5988735).

Almost surely, 2^51515920 is an apocalyptic number.

It is an amenable number.

51515920 is an abundant number, since it is smaller than the sum of its proper divisors (68258780).

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

51515920 is a wasteful number, since it uses less digits than its factorization.

51515920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 643962 (or 643956 counting only the distinct ones).

The product of its (nonzero) digits is 2250, while the sum is 28.

The square root of 51515920 is about 7177.4591604550. The cubic root of 51515920 is about 372.0892759870.

The spelling of 51515920 in words is "fifty-one million, five hundred fifteen thousand, nine hundred twenty".