51287209 has 2 divisors, whose sum is σ = 51287210. Its totient is φ = 51287208.

The previous prime is 51287191. The next prime is 51287219. The reversal of 51287209 is 90278215.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51265600 + 21609 = 7160^2 + 147^2 .

It is a cyclic number.

It is not a de Polignac number, because 51287209 - 2¹³ = 51279017 is a prime.

It is not a weakly prime, because it can be changed into another prime (51287219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25643604 + 25643605.

It is an arithmetic number, because the mean of its divisors is an integer number (25643605).

Almost surely, 2^51287209 is an apocalyptic number.

It is an amenable number.

51287209 is a deficient number, since it is larger than the sum of its proper divisors (1).

51287209 is an equidigital number, since it uses as much as digits as its factorization.

51287209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 51287209 is about 7161.5088493976. The cubic root of 51287209 is about 371.5378143517.

The spelling of 51287209 in words is "fifty-one million, two hundred eighty-seven thousand, two hundred nine".