655560991 has 2 divisors, whose sum is σ = 655560992. Its totient is φ = 655560990.

The previous prime is 655560967. The next prime is 655561001. The reversal of 655560991 is 199065556.

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-655560991 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (655560911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 327780495 + 327780496.

It is an arithmetic number, because the mean of its divisors is an integer number (327780496).

Almost surely, 2^655560991 is an apocalyptic number.

655560991 is a deficient number, since it is larger than the sum of its proper divisors (1).

655560991 is an equidigital number, since it uses as much as digits as its factorization.

655560991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 364500, while the sum is 46.

The square root of 655560991 is about 25603.9253045309. The cubic root of 655560991 is about 868.7024260062.

The spelling of 655560991 in words is "six hundred fifty-five million, five hundred sixty thousand, nine hundred ninety-one".