51663281 has 2 divisors, whose sum is σ = 51663282. Its totient is φ = 51663280.

The previous prime is 51663263. The next prime is 51663307. The reversal of 51663281 is 18236615.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 46022656 + 5640625 = 6784^2 + 2375^2 .

It is a cyclic number.

It is not a de Polignac number, because 51663281 - 2¹⁴ = 51646897 is a prime.

It is a super-2 number, since 2×51663281² = 5338189207369922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is equal to p_3094835 and since 51663281 and 3094835 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (51663251) 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, 25831640 + 25831641.

It is an arithmetic number, because the mean of its divisors is an integer number (25831641).

Almost surely, 2^51663281 is an apocalyptic number.

It is an amenable number.

51663281 is a deficient number, since it is larger than the sum of its proper divisors (1).

51663281 is an equidigital number, since it uses as much as digits as its factorization.

51663281 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8640, while the sum is 32.

The square root of 51663281 is about 7187.7173706261. The cubic root of 51663281 is about 372.4437246638.

Adding to 51663281 its reverse (18236615), we get a palindrome (69899896).

The spelling of 51663281 in words is "fifty-one million, six hundred sixty-three thousand, two hundred eighty-one".