51387981844949 has 2 divisors, whose sum is σ = 51387981844950. Its totient is φ = 51387981844948.

The previous prime is 51387981844931. The next prime is 51387981844981. The reversal of 51387981844949 is 94944818978315.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 34124372342449 + 17263609502500 = 5841607^2 + 4154950^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51387981844949 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51387981843949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25693990922474 + 25693990922475.

It is an arithmetic number, because the mean of its divisors is an integer number (25693990922475).

Almost surely, 2^{51387981844949} is an apocalyptic number.

It is an amenable number.

51387981844949 is a deficient number, since it is larger than the sum of its proper divisors (1).

51387981844949 is an equidigital number, since it uses as much as digits as its factorization.

51387981844949 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2508226560, while the sum is 80.

The spelling of 51387981844949 in words is "fifty-one trillion, three hundred eighty-seven billion, nine hundred eighty-one million, eight hundred forty-four thousand, nine hundred forty-nine".