660606691 has 2 divisors, whose sum is σ = 660606692. Its totient is φ = 660606690.

The previous prime is 660606679. The next prime is 660606697. The reversal of 660606691 is 196606066.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-660606691 is a prime.

It is not a weakly prime, because it can be changed into another prime (660606697) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330303345 + 330303346.

It is an arithmetic number, because the mean of its divisors is an integer number (330303346).

Almost surely, 2^660606691 is an apocalyptic number.

660606691 is a deficient number, since it is larger than the sum of its proper divisors (1).

660606691 is an equidigital number, since it uses as much as digits as its factorization.

660606691 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 69984, while the sum is 40.

The square root of 660606691 is about 25702.2701526538. The cubic root of 660606691 is about 870.9254656173.

The spelling of 660606691 in words is "six hundred sixty million, six hundred six thousand, six hundred ninety-one".