51091309 has 2 divisors, whose sum is σ = 51091310. Its totient is φ = 51091308.

The previous prime is 51091291. The next prime is 51091321. The reversal of 51091309 is 90319015.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 40832100 + 10259209 = 6390^2 + 3203^2 .

It is a cyclic number.

It is not a de Polignac number, because 51091309 - 2¹¹ = 51089261 is a prime.

It is a super-2 number, since 2×51091309² = 5220643710666962, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51091609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25545654 + 25545655.

It is an arithmetic number, because the mean of its divisors is an integer number (25545655).

Almost surely, 2^51091309 is an apocalyptic number.

It is an amenable number.

51091309 is a deficient number, since it is larger than the sum of its proper divisors (1).

51091309 is an equidigital number, since it uses as much as digits as its factorization.

51091309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1215, while the sum is 28.

The square root of 51091309 is about 7147.8184783891. The cubic root of 51091309 is about 371.0641606739.

It can be divided in two parts, 510 and 91309, that added together give a palindrome (91819).

The spelling of 51091309 in words is "fifty-one million, ninety-one thousand, three hundred nine".