11551581 has 6 divisors (see below), whose sum is σ = 16685630. Its totient is φ = 7701048.

The previous prime is 11551567. The next prime is 11551583. The reversal of 11551581 is 18515511.

11551581 is digitally balanced in base 3, 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 only one way, i.e., 7784100 + 3767481 = 2790^2 + 1941^2 .

It is not a de Polignac number, because 11551581 - 2⁷ = 11551453 is a prime.

It is a super-2 number, since 2×11551581² = 266878047199122, 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 (11551583) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 641746 + ... + 641763.

Almost surely, 2^11551581 is an apocalyptic number.

It is an amenable number.

11551581 is a deficient number, since it is larger than the sum of its proper divisors (5134049).

11551581 is a wasteful number, since it uses less digits than its factorization.

11551581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1283515 (or 1283512 counting only the distinct ones).

The product of its digits is 1000, while the sum is 27.

The square root of 11551581 is about 3398.7616862616. The cubic root of 11551581 is about 226.0548395909.

The spelling of 11551581 in words is "eleven million, five hundred fifty-one thousand, five hundred eighty-one".