51861281 has 2 divisors, whose sum is σ = 51861282. Its totient is φ = 51861280.

The previous prime is 51861247. The next prime is 51861287. The reversal of 51861281 is 18216815.

51861281 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 40436881 + 11424400 = 6359^2 + 3380^2 .

It is a cyclic number.

It is not a de Polignac number, because 51861281 - 2¹⁸ = 51599137 is a prime.

It is a super-2 number, since 2×51861281² = 5379184933921922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (51861287) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25930640 + 25930641.

It is an arithmetic number, because the mean of its divisors is an integer number (25930641).

Almost surely, 2^51861281 is an apocalyptic number.

It is an amenable number.

51861281 is a deficient number, since it is larger than the sum of its proper divisors (1).

51861281 is an equidigital number, since it uses as much as digits as its factorization.

51861281 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3840, while the sum is 32.

The square root of 51861281 is about 7201.4776955844. The cubic root of 51861281 is about 372.9189161224.

The spelling of 51861281 in words is "fifty-one million, eight hundred sixty-one thousand, two hundred eighty-one".