2666520209 has 2 divisors, whose sum is σ = 2666520210. Its totient is φ = 2666520208.

The previous prime is 2666520179. The next prime is 2666520253. The reversal of 2666520209 is 9020256662.

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., 1929669184 + 736851025 = 43928^2 + 27145^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2666520209 is a prime.

It is a super-2 number, since 2×2666520209² = 14220660050010807362, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (2666520289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1333260104 + 1333260105.

It is an arithmetic number, because the mean of its divisors is an integer number (1333260105).

Almost surely, 2^2666520209 is an apocalyptic number.

It is an amenable number.

2666520209 is a deficient number, since it is larger than the sum of its proper divisors (1).

2666520209 is an equidigital number, since it uses as much as digits as its factorization.

2666520209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 77760, while the sum is 38.

The square root of 2666520209 is about 51638.3598597012. The cubic root of 2666520209 is about 1386.6971612179.

The spelling of 2666520209 in words is "two billion, six hundred sixty-six million, five hundred twenty thousand, two hundred nine".