2661669581 has 2 divisors, whose sum is σ = 2661669582. Its totient is φ = 2661669580.

The previous prime is 2661669559. The next prime is 2661669623. The reversal of 2661669581 is 1859661662.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2238709225 + 422960356 = 47315^2 + 20566^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2661669581 is a prime.

It is a super-2 number, since 2×2661669581² = 14168969916841431122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2661669551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1330834790 + 1330834791.

It is an arithmetic number, because the mean of its divisors is an integer number (1330834791).

Almost surely, 2^2661669581 is an apocalyptic number.

It is an amenable number.

2661669581 is a deficient number, since it is larger than the sum of its proper divisors (1).

2661669581 is an equidigital number, since it uses as much as digits as its factorization.

2661669581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 933120, while the sum is 50.

The square root of 2661669581 is about 51591.3711874379. The cubic root of 2661669581 is about 1385.8558106586.

The spelling of 2661669581 in words is "two billion, six hundred sixty-one million, six hundred sixty-nine thousand, five hundred eighty-one".