2661689 has 2 divisors, whose sum is σ = 2661690. Its totient is φ = 2661688.

The previous prime is 2661661. The next prime is 2661731. The reversal of 2661689 is 9861662.

2661689 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2199289 + 462400 = 1483^2 + 680^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2661689 is a prime.

It is a plaindrome in base 15.

It is not a weakly prime, because it can be changed into another prime (2661089) 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, 1330844 + 1330845.

It is an arithmetic number, because the mean of its divisors is an integer number (1330845).

2^2661689 is an apocalyptic number.

It is an amenable number.

2661689 is a deficient number, since it is larger than the sum of its proper divisors (1).

2661689 is an equidigital number, since it uses as much as digits as its factorization.

2661689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31104, while the sum is 38.

The square root of 2661689 is about 1631.4683570330. The cubic root of 2661689 is about 138.5859180958.

The spelling of 2661689 in words is "two million, six hundred sixty-one thousand, six hundred eighty-nine".