2005261681 has 2 divisors, whose sum is σ = 2005261682. Its totient is φ = 2005261680.

The previous prime is 2005261669. The next prime is 2005261703. The reversal of 2005261681 is 1861625002.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1089594081 + 915667600 = 33009^2 + 30260^2 .

It is a cyclic number.

It is not a de Polignac number, because 2005261681 - 2⁵ = 2005261649 is a prime.

It is a super-2 number, since 2×2005261681² = 8042148818573891522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (2005261631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1002630840 + 1002630841.

It is an arithmetic number, because the mean of its divisors is an integer number (1002630841).

Almost surely, 2^2005261681 is an apocalyptic number.

It is an amenable number.

2005261681 is a deficient number, since it is larger than the sum of its proper divisors (1).

2005261681 is an equidigital number, since it uses as much as digits as its factorization.

2005261681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 2005261681 is about 44780.1482914025. The cubic root of 2005261681 is about 1261.0249661592.

Adding to 2005261681 its reverse (1861625002), we get a palindrome (3866886683).

The spelling of 2005261681 in words is "two billion, five million, two hundred sixty-one thousand, six hundred eighty-one".