2661682781 has 2 divisors, whose sum is σ = 2661682782. Its totient is φ = 2661682780.

The previous prime is 2661682769. The next prime is 2661682787. The reversal of 2661682781 is 1872861662.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1961604100 + 700078681 = 44290^2 + 26459^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2661682781 is a prime.

It is a super-2 number, since 2×2661682781² = 14169110453343787922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2661682787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1330841390 + 1330841391.

It is an arithmetic number, because the mean of its divisors is an integer number (1330841391).

Almost surely, 2^2661682781 is an apocalyptic number.

It is an amenable number.

2661682781 is a deficient number, since it is larger than the sum of its proper divisors (1).

2661682781 is an equidigital number, since it uses as much as digits as its factorization.

2661682781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 387072, while the sum is 47.

The square root of 2661682781 is about 51591.4991156489. The cubic root of 2661682781 is about 1385.8581016099.

The spelling of 2661682781 in words is "two billion, six hundred sixty-one million, six hundred eighty-two thousand, seven hundred eighty-one".