51511891 has 2 divisors, whose sum is σ = 51511892. Its totient is φ = 51511890.

The previous prime is 51511879. The next prime is 51511913. The reversal of 51511891 is 19811515.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 51511891 - 2⁷ = 51511763 is a prime.

It is not a weakly prime, because it can be changed into another prime (51511861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25755945 + 25755946.

It is an arithmetic number, because the mean of its divisors is an integer number (25755946).

Almost surely, 2^51511891 is an apocalyptic number.

51511891 is a deficient number, since it is larger than the sum of its proper divisors (1).

51511891 is an equidigital number, since it uses as much as digits as its factorization.

51511891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1800, while the sum is 31.

The square root of 51511891 is about 7177.1784846136. The cubic root of 51511891 is about 372.0795755114.

The spelling of 51511891 in words is "fifty-one million, five hundred eleven thousand, eight hundred ninety-one".