2666861 has 2 divisors, whose sum is σ = 2666862. Its totient is φ = 2666860.

The previous prime is 2666819. The next prime is 2666863. The reversal of 2666861 is 1686662.

2666861 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2540836 + 126025 = 1594^2 + 355^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2666861 is a prime.

It is a super-2 number, since 2×2666861² = 14224295186642, which contains 22 as substring.

Together with 2666863, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2666863) 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, 1333430 + 1333431.

It is an arithmetic number, because the mean of its divisors is an integer number (1333431).

2^2666861 is an apocalyptic number.

It is an amenable number.

2666861 is a deficient number, since it is larger than the sum of its proper divisors (1).

2666861 is an equidigital number, since it uses as much as digits as its factorization.

2666861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20736, while the sum is 35.

The square root of 2666861 is about 1633.0526629598. The cubic root of 2666861 is about 138.6756233685.

The spelling of 2666861 in words is "two million, six hundred sixty-six thousand, eight hundred sixty-one".