51491689 has 2 divisors, whose sum is σ = 51491690. Its totient is φ = 51491688.

The previous prime is 51491681. The next prime is 51491701. The reversal of 51491689 is 98619415.

51491689 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., 43454464 + 8037225 = 6592^2 + 2835^2 .

It is a cyclic number.

It is not a de Polignac number, because 51491689 - 2³ = 51491681 is a prime.

It is not a weakly prime, because it can be changed into another prime (51491681) 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, 25745844 + 25745845.

It is an arithmetic number, because the mean of its divisors is an integer number (25745845).

Almost surely, 2^51491689 is an apocalyptic number.

It is an amenable number.

51491689 is a deficient number, since it is larger than the sum of its proper divisors (1).

51491689 is an equidigital number, since it uses as much as digits as its factorization.

51491689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 77760, while the sum is 43.

The square root of 51491689 is about 7175.7709690318. The cubic root of 51491689 is about 372.0309282683.

The spelling of 51491689 in words is "fifty-one million, four hundred ninety-one thousand, six hundred eighty-nine".