51716561 has 4 divisors (see below), whose sum is σ = 55694772. Its totient is φ = 47738352.

The previous prime is 51716543. The next prime is 51716579. The reversal of 51716561 is 16561715.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (51716543) and next prime (51716579).

It can be written as a sum of positive squares in 2 ways, for example, as 19009600 + 32706961 = 4360^2 + 5719^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51716561 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (51716531) 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 3 ways as a sum of consecutive naturals, for example, 1989086 + ... + 1989111.

It is an arithmetic number, because the mean of its divisors is an integer number (13923693).

Almost surely, 2^51716561 is an apocalyptic number.

It is an amenable number.

51716561 is a deficient number, since it is larger than the sum of its proper divisors (3978211).

51716561 is a wasteful number, since it uses less digits than its factorization.

51716561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3978210.

The product of its digits is 6300, while the sum is 32.

The square root of 51716561 is about 7191.4227382348. The cubic root of 51716561 is about 372.5717135925.

The spelling of 51716561 in words is "fifty-one million, seven hundred sixteen thousand, five hundred sixty-one".