51511561 has 2 divisors, whose sum is σ = 51511562. Its totient is φ = 51511560.

The previous prime is 51511541. The next prime is 51511591. The reversal of 51511561 is 16511515.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 44302336 + 7209225 = 6656^2 + 2685^2 .

It is a cyclic number.

It is not a de Polignac number, because 51511561 - 2⁵ = 51511529 is a prime.

It is not a weakly prime, because it can be changed into another prime (51511531) 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 as a sum of consecutive naturals, namely, 25755780 + 25755781.

It is an arithmetic number, because the mean of its divisors is an integer number (25755781).

Almost surely, 2^51511561 is an apocalyptic number.

It is an amenable number.

51511561 is a deficient number, since it is larger than the sum of its proper divisors (1).

51511561 is an equidigital number, since it uses as much as digits as its factorization.

51511561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 750, while the sum is 25.

The square root of 51511561 is about 7177.1554950412. The cubic root of 51511561 is about 372.0787809600.

The spelling of 51511561 in words is "fifty-one million, five hundred eleven thousand, five hundred sixty-one".