51289891 has 2 divisors, whose sum is σ = 51289892. Its totient is φ = 51289890.

The previous prime is 51289879. The next prime is 51289913. The reversal of 51289891 is 19898215.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 51289891 - 2²¹ = 49192739 is a prime.

It is not a weakly prime, because it can be changed into another prime (51289871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25644945 + 25644946.

It is an arithmetic number, because the mean of its divisors is an integer number (25644946).

Almost surely, 2^51289891 is an apocalyptic number.

51289891 is a deficient number, since it is larger than the sum of its proper divisors (1).

51289891 is an equidigital number, since it uses as much as digits as its factorization.

51289891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51840, while the sum is 43.

The square root of 51289891 is about 7161.6960979924. The cubic root of 51289891 is about 371.5442906062.

The spelling of 51289891 in words is "fifty-one million, two hundred eighty-nine thousand, eight hundred ninety-one".