2123581 has 2 divisors, whose sum is σ = 2123582. Its totient is φ = 2123580.

The previous prime is 2123557. The next prime is 2123603. The reversal of 2123581 is 1853212.

2123581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an a-pointer prime, because the next prime (2123603) can be obtained adding 2123581 to its sum of digits (22).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1428025 + 695556 = 1195^2 + 834^2 .

It is a cyclic number.

It is not a de Polignac number, because 2123581 - 2¹⁷ = 1992509 is a prime.

It is a super-2 number, since 2×2123581² = 9019192527122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2123081) 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 as a sum of consecutive naturals, namely, 1061790 + 1061791.

It is an arithmetic number, because the mean of its divisors is an integer number (1061791).

2^2123581 is an apocalyptic number.

It is an amenable number.

2123581 is a deficient number, since it is larger than the sum of its proper divisors (1).

2123581 is an equidigital number, since it uses as much as digits as its factorization.

2123581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 480, while the sum is 22.

The square root of 2123581 is about 1457.2511794471. The cubic root of 2123581 is about 128.5354563092.

Adding to 2123581 its reverse (1853212), we get a palindrome (3976793).

It can be divided in two parts, 21235 and 81, that added together give a square (21316 = 146²).

The spelling of 2123581 in words is "two million, one hundred twenty-three thousand, five hundred eighty-one".