13001581 has 4 divisors (see below), whose sum is σ = 13009792. Its totient is φ = 12993372.

The previous prime is 13001557. The next prime is 13001603. The reversal of 13001581 is 18510031.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 13001581 - 2¹¹ = 12999533 is a prime.

It is a super-2 number, since 2×13001581² = 338082216999122, 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 (13001501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 891 + ... + 5176.

It is an arithmetic number, because the mean of its divisors is an integer number (3252448).

Almost surely, 2^13001581 is an apocalyptic number.

It is an amenable number.

13001581 is a deficient number, since it is larger than the sum of its proper divisors (8211).

13001581 is an equidigital number, since it uses as much as digits as its factorization.

13001581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8210.

The product of its (nonzero) digits is 120, while the sum is 19.

The square root of 13001581 is about 3605.7705140511. The cubic root of 13001581 is about 235.1430003348.

The spelling of 13001581 in words is "thirteen million, one thousand, five hundred eighty-one".