2661666645109 has 2 divisors, whose sum is σ = 2661666645110. Its totient is φ = 2661666645108.

The previous prime is 2661666645107. The next prime is 2661666645133. The reversal of 2661666645109 is 9015466661662.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1961741986884 + 699924658225 = 1400622^2 + 836615^2 .

It is a cyclic number.

It is not a de Polignac number, because 2661666645109 - 2¹ = 2661666645107 is a prime.

Together with 2661666645107, 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 (2661666645107) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1330833322554 + 1330833322555.

It is an arithmetic number, because the mean of its divisors is an integer number (1330833322555).

Almost surely, 2^{2661666645109} is an apocalyptic number.

It is an amenable number.

2661666645109 is a deficient number, since it is larger than the sum of its proper divisors (1).

2661666645109 is an equidigital number, since it uses as much as digits as its factorization.

2661666645109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16796160, while the sum is 58.

The spelling of 2661666645109 in words is "two trillion, six hundred sixty-one billion, six hundred sixty-six million, six hundred forty-five thousand, one hundred nine".