2581861 has 2 divisors, whose sum is σ = 2581862. Its totient is φ = 2581860.

The previous prime is 2581847. The next prime is 2581877. The reversal of 2581861 is 1681852.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1640961 + 940900 = 1281^2 + 970^2 .

It is a cyclic number.

It is not a de Polignac number, because 2581861 - 2⁵ = 2581829 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2581561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1290930 + 1290931.

It is an arithmetic number, because the mean of its divisors is an integer number (1290931).

2^2581861 is an apocalyptic number.

It is an amenable number.

2581861 is a deficient number, since it is larger than the sum of its proper divisors (1).

2581861 is an equidigital number, since it uses as much as digits as its factorization.

2581861 is an evil number, because the sum of its binary digits is even.

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

The square root of 2581861 is about 1606.8170399893. The cubic root of 2581861 is about 137.1863661452.

Subtracting from 2581861 its reverse (1681852), we obtain a palindrome (900009).

The spelling of 2581861 in words is "two million, five hundred eighty-one thousand, eight hundred sixty-one".