6661509091 has 2 divisors, whose sum is σ = 6661509092. Its totient is φ = 6661509090.

The previous prime is 6661509083. The next prime is 6661509137. The reversal of 6661509091 is 1909051666.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 6661509091 - 2³ = 6661509083 is a prime.

It is not a weakly prime, because it can be changed into another prime (6661509031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3330754545 + 3330754546.

It is an arithmetic number, because the mean of its divisors is an integer number (3330754546).

Almost surely, 2^6661509091 is an apocalyptic number.

6661509091 is a deficient number, since it is larger than the sum of its proper divisors (1).

6661509091 is an equidigital number, since it uses as much as digits as its factorization.

6661509091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 87480, while the sum is 43.

The square root of 6661509091 is about 81618.0684101260. The cubic root of 6661509091 is about 1881.5865860953.

The spelling of 6661509091 in words is "six billion, six hundred sixty-one million, five hundred nine thousand, ninety-one".