2643661 has 2 divisors, whose sum is σ = 2643662. Its totient is φ = 2643660.

The previous prime is 2643659. The next prime is 2643671. The reversal of 2643661 is 1663462.

2643661 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., 2621161 + 22500 = 1619^2 + 150^2 .

It is a cyclic number.

It is not a de Polignac number, because 2643661 - 2¹ = 2643659 is a prime.

Together with 2643659, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2643671) 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, 1321830 + 1321831.

It is an arithmetic number, because the mean of its divisors is an integer number (1321831).

2^2643661 is an apocalyptic number.

It is an amenable number.

2643661 is a deficient number, since it is larger than the sum of its proper divisors (1).

2643661 is an equidigital number, since it uses as much as digits as its factorization.

2643661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 28.

The square root of 2643661 is about 1625.9338854947. The cubic root of 2643661 is about 138.2723216053.

The spelling of 2643661 in words is "two million, six hundred forty-three thousand, six hundred sixty-one".