11111581 has 12 divisors (see below), whose sum is σ = 12364212. Its totient is φ = 9974016.

The previous prime is 11111579. The next prime is 11111621. The reversal of 11111581 is 18511111.

11111581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 6 ways, for example, as 280900 + 10830681 = 530^2 + 3291^2 .

It is not a de Polignac number, because 11111581 - 2¹ = 11111579 is a prime.

It is a super-2 number, since 2×11111581² = 246934464639122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11111531) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5365 + ... + 7141.

It is an arithmetic number, because the mean of its divisors is an integer number (1030351).

Almost surely, 2^11111581 is an apocalyptic number.

It is an amenable number.

11111581 is a deficient number, since it is larger than the sum of its proper divisors (1252631).

11111581 is a wasteful number, since it uses less digits than its factorization.

11111581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1840 (or 1827 counting only the distinct ones).

The product of its digits is 40, while the sum is 19.

The square root of 11111581 is about 3333.4038159215. The cubic root of 11111581 is about 223.1474622408.

Adding to 11111581 its reverse (18511111), we get a palindrome (29622692).

The spelling of 11111581 in words is "eleven million, one hundred eleven thousand, five hundred eighty-one".