51177781 has 2 divisors, whose sum is σ = 51177782. Its totient is φ = 51177780.

The previous prime is 51177767. The next prime is 51177827. The reversal of 51177781 is 18777115.

It is a happy number.

51177781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50552100 + 625681 = 7110^2 + 791^2 .

It is a cyclic number.

It is not a de Polignac number, because 51177781 - 2⁷ = 51177653 is a prime.

It is a super-2 number, since 2×51177781² = 5238330536167922, 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 51177781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51175781) 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, 25588890 + 25588891.

It is an arithmetic number, because the mean of its divisors is an integer number (25588891).

Almost surely, 2^51177781 is an apocalyptic number.

It is an amenable number.

51177781 is a deficient number, since it is larger than the sum of its proper divisors (1).

51177781 is an equidigital number, since it uses as much as digits as its factorization.

51177781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13720, while the sum is 37.

The square root of 51177781 is about 7153.8647596946. The cubic root of 51177781 is about 371.2733846138.

The spelling of 51177781 in words is "fifty-one million, one hundred seventy-seven thousand, seven hundred eighty-one".