2861581 has 4 divisors (see below), whose sum is σ = 2865564. Its totient is φ = 2857600.

The previous prime is 2861569. The next prime is 2861587. The reversal of 2861581 is 1851682.

2861581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2418025 + 443556 = 1555^2 + 666^2 .

It is a cyclic number.

It is not a de Polignac number, because 2861581 - 2⁵ = 2861549 is a prime.

It is a super-2 number, since 2×2861581² = 16377291639122, which contains 22 as substring.

It is an Ulam 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 (2861587) 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 3 ways as a sum of consecutive naturals, for example, 580 + ... + 2461.

It is an arithmetic number, because the mean of its divisors is an integer number (716391).

2^2861581 is an apocalyptic number.

It is an amenable number.

2861581 is a deficient number, since it is larger than the sum of its proper divisors (3983).

2861581 is an equidigital number, since it uses as much as digits as its factorization.

2861581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3982.

The product of its digits is 3840, while the sum is 31.

The square root of 2861581 is about 1691.6208203968. The cubic root of 2861581 is about 141.9717757830.

The spelling of 2861581 in words is "two million, eight hundred sixty-one thousand, five hundred eighty-one".