51312561 has 4 divisors (see below), whose sum is σ = 68416752. Its totient is φ = 34208372.

The previous prime is 51312551. The next prime is 51312577. The reversal of 51312561 is 16521315.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 51312561 - 2⁶ = 51312497 is a prime.

It is not an unprimeable number, because it can be changed into a prime (51312551) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8552091 + ... + 8552096.

It is an arithmetic number, because the mean of its divisors is an integer number (17104188).

Almost surely, 2^51312561 is an apocalyptic number.

It is an amenable number.

51312561 is a deficient number, since it is larger than the sum of its proper divisors (17104191).

51312561 is a wasteful number, since it uses less digits than its factorization.

51312561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17104190.

The product of its digits is 900, while the sum is 24.

The square root of 51312561 is about 7163.2786487753. The cubic root of 51312561 is about 371.5990230836.

Adding to 51312561 its reverse (16521315), we get a palindrome (67833876).

The spelling of 51312561 in words is "fifty-one million, three hundred twelve thousand, five hundred sixty-one".