51817681 has 2 divisors, whose sum is σ = 51817682. Its totient is φ = 51817680.

The previous prime is 51817627. The next prime is 51817687. The reversal of 51817681 is 18671815.

51817681 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., 50339025 + 1478656 = 7095^2 + 1216^2 .

It is a cyclic number.

It is not a de Polignac number, because 51817681 - 2¹¹ = 51815633 is a prime.

It is a super-2 number, since 2×51817681² = 5370144128435522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 51817681.

It is not a weakly prime, because it can be changed into another prime (51817687) 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, 25908840 + 25908841.

It is an arithmetic number, because the mean of its divisors is an integer number (25908841).

Almost surely, 2^51817681 is an apocalyptic number.

It is an amenable number.

51817681 is a deficient number, since it is larger than the sum of its proper divisors (1).

51817681 is an equidigital number, since it uses as much as digits as its factorization.

51817681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13440, while the sum is 37.

The square root of 51817681 is about 7198.4499025832. The cubic root of 51817681 is about 372.8143819820.

The spelling of 51817681 in words is "fifty-one million, eight hundred seventeen thousand, six hundred eighty-one".