11855581 has 2 divisors, whose sum is σ = 11855582. Its totient is φ = 11855580.

The previous prime is 11855567. The next prime is 11855593. The reversal of 11855581 is 18555811.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11329956 + 525625 = 3366^2 + 725^2 .

It is a cyclic number.

It is not a de Polignac number, because 11855581 - 2⁵ = 11855549 is a prime.

It is a super-2 number, since 2×11855581² = 281109601695122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11855521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5927790 + 5927791.

It is an arithmetic number, because the mean of its divisors is an integer number (5927791).

Almost surely, 2^11855581 is an apocalyptic number.

It is an amenable number.

11855581 is a deficient number, since it is larger than the sum of its proper divisors (1).

11855581 is an equidigital number, since it uses as much as digits as its factorization.

11855581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8000, while the sum is 34.

The square root of 11855581 is about 3443.1934305235. The cubic root of 11855581 is about 228.0207032088.

The spelling of 11855581 in words is "eleven million, eight hundred fifty-five thousand, five hundred eighty-one".