51516281 has 2 divisors, whose sum is σ = 51516282. Its totient is φ = 51516280.

The previous prime is 51516271. The next prime is 51516293. The reversal of 51516281 is 18261515.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 29800681 + 21715600 = 5459^2 + 4660^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51516281 is a prime.

It is a super-2 number, since 2×51516281² = 5307854416141922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (51516221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25758140 + 25758141.

It is an arithmetic number, because the mean of its divisors is an integer number (25758141).

Almost surely, 2^51516281 is an apocalyptic number.

It is an amenable number.

51516281 is a deficient number, since it is larger than the sum of its proper divisors (1).

51516281 is an equidigital number, since it uses as much as digits as its factorization.

51516281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2400, while the sum is 29.

The square root of 51516281 is about 7177.4843085861. The cubic root of 51516281 is about 372.0901451287.

Adding to 51516281 its reverse (18261515), we get a palindrome (69777796).

The spelling of 51516281 in words is "fifty-one million, five hundred sixteen thousand, two hundred eighty-one".