51161681 has 2 divisors, whose sum is σ = 51161682. Its totient is φ = 51161680.

The previous prime is 51161659. The next prime is 51161689. The reversal of 51161681 is 18616115.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 47831056 + 3330625 = 6916^2 + 1825^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51161681 is a prime.

It is a super-2 number, since 2×51161681² = 5235035205491522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (51161689) 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 as a sum of consecutive naturals, namely, 25580840 + 25580841.

It is an arithmetic number, because the mean of its divisors is an integer number (25580841).

Almost surely, 2^51161681 is an apocalyptic number.

It is an amenable number.

51161681 is a deficient number, since it is larger than the sum of its proper divisors (1).

51161681 is an equidigital number, since it uses as much as digits as its factorization.

51161681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1440, while the sum is 29.

The square root of 51161681 is about 7152.7394052908. The cubic root of 51161681 is about 371.2344476096.

Adding to 51161681 its reverse (18616115), we get a palindrome (69777796).

The spelling of 51161681 in words is "fifty-one million, one hundred sixty-one thousand, six hundred eighty-one".