11865509 has 2 divisors, whose sum is σ = 11865510. Its totient is φ = 11865508.

The previous prime is 11865487. The next prime is 11865521. The reversal of 11865509 is 90556811.

11865509 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10543009 + 1322500 = 3247^2 + 1150^2 .

It is an emirp because it is prime and its reverse (90556811) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 11865509 - 2¹² = 11861413 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11865409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5932754 + 5932755.

It is an arithmetic number, because the mean of its divisors is an integer number (5932755).

Almost surely, 2^11865509 is an apocalyptic number.

It is an amenable number.

11865509 is a deficient number, since it is larger than the sum of its proper divisors (1).

11865509 is an equidigital number, since it uses as much as digits as its factorization.

11865509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10800, while the sum is 35.

The square root of 11865509 is about 3444.6348137357. The cubic root of 11865509 is about 228.0843345041.

The spelling of 11865509 in words is "eleven million, eight hundred sixty-five thousand, five hundred nine".