11516581 has 2 divisors, whose sum is σ = 11516582. Its totient is φ = 11516580.

The previous prime is 11516579. The next prime is 11516663. The reversal of 11516581 is 18561511.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10432900 + 1083681 = 3230^2 + 1041^2 .

It is an emirp because it is prime and its reverse (18561511) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 11516581 - 2¹ = 11516579 is a prime.

It is a super-2 number, since 2×11516581² = 265263275859122, which contains 22 as substring.

Together with 11516579, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11516521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5758290 + 5758291.

It is an arithmetic number, because the mean of its divisors is an integer number (5758291).

Almost surely, 2^11516581 is an apocalyptic number.

It is an amenable number.

11516581 is a deficient number, since it is larger than the sum of its proper divisors (1).

11516581 is an equidigital number, since it uses as much as digits as its factorization.

11516581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1200, while the sum is 28.

The square root of 11516581 is about 3393.6088460516. The cubic root of 11516581 is about 225.8263016500.

The spelling of 11516581 in words is "eleven million, five hundred sixteen thousand, five hundred eighty-one".