51809987 has 2 divisors, whose sum is σ = 51809988. Its totient is φ = 51809986.

The previous prime is 51809977. The next prime is 51809993. The reversal of 51809987 is 78990815.

It is a happy number.

51809987 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 is a cyclic number.

It is not a de Polignac number, because 51809987 - 2⁴ = 51809971 is a prime.

It is not a weakly prime, because it can be changed into another prime (51809917) 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, 25904993 + 25904994.

It is an arithmetic number, because the mean of its divisors is an integer number (25904994).

Almost surely, 2^51809987 is an apocalyptic number.

51809987 is a deficient number, since it is larger than the sum of its proper divisors (1).

51809987 is an equidigital number, since it uses as much as digits as its factorization.

51809987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 181440, while the sum is 47.

The square root of 51809987 is about 7197.9154621321. The cubic root of 51809987 is about 372.7959289766.

The spelling of 51809987 in words is "fifty-one million, eight hundred nine thousand, nine hundred eighty-seven".