2113581 has 4 divisors (see below), whose sum is σ = 2818112. Its totient is φ = 1409052.

The previous prime is 2113567. The next prime is 2113583. The reversal of 2113581 is 1853112.

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.

It is not a de Polignac number, because 2113581 - 2¹¹ = 2111533 is a prime.

It is a super-2 number, since 2×2113581² = 8934449287122, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2113583) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 352261 + ... + 352266.

It is an arithmetic number, because the mean of its divisors is an integer number (704528).

2^2113581 is an apocalyptic number.

It is an amenable number.

2113581 is a deficient number, since it is larger than the sum of its proper divisors (704531).

2113581 is an equidigital number, since it uses as much as digits as its factorization.

2113581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 704530.

The product of its digits is 240, while the sum is 21.

The square root of 2113581 is about 1453.8160131186. The cubic root of 2113581 is about 128.3333798092. Note that the first 4 decimals are identical.

Adding to 2113581 its reverse (1853112), we get a palindrome (3966693).

The spelling of 2113581 in words is "two million, one hundred thirteen thousand, five hundred eighty-one".