51315521 has 2 divisors, whose sum is σ = 51315522. Its totient is φ = 51315520.

The previous prime is 51315499. The next prime is 51315547. The reversal of 51315521 is 12551315.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 38925121 + 12390400 = 6239^2 + 3520^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51315521 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (51315721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25657760 + 25657761.

It is an arithmetic number, because the mean of its divisors is an integer number (25657761).

Almost surely, 2^51315521 is an apocalyptic number.

It is an amenable number.

51315521 is a deficient number, since it is larger than the sum of its proper divisors (1).

51315521 is an equidigital number, since it uses as much as digits as its factorization.

51315521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 750, while the sum is 23.

The square root of 51315521 is about 7163.4852550975. The cubic root of 51315521 is about 371.6061682604.

Adding to 51315521 its reverse (12551315), we get a palindrome (63866836).

The spelling of 51315521 in words is "fifty-one million, three hundred fifteen thousand, five hundred twenty-one".