2666397581 has 2 divisors, whose sum is σ = 2666397582. Its totient is φ = 2666397580.

The previous prime is 2666397571. The next prime is 2666397611. The reversal of 2666397581 is 1857936662.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2179489225 + 486908356 = 46685^2 + 22066^2 .

It is a cyclic number.

It is not a de Polignac number, because 2666397581 - 2²⁶ = 2599288717 is a prime.

It is a super-2 number, since 2×2666397581² = 14219352119925303122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2666397551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1333198790 + 1333198791.

It is an arithmetic number, because the mean of its divisors is an integer number (1333198791).

Almost surely, 2^2666397581 is an apocalyptic number.

It is an amenable number.

2666397581 is a deficient number, since it is larger than the sum of its proper divisors (1).

2666397581 is an equidigital number, since it uses as much as digits as its factorization.

2666397581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3265920, while the sum is 53.

The square root of 2666397581 is about 51637.1724729385. The cubic root of 2666397581 is about 1386.6759037371.

The spelling of 2666397581 in words is "two billion, six hundred sixty-six million, three hundred ninety-seven thousand, five hundred eighty-one".