660538391 has 2 divisors, whose sum is σ = 660538392. Its totient is φ = 660538390.

The previous prime is 660538367. The next prime is 660538397. The reversal of 660538391 is 193835066.

660538391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 660538391 - 2¹⁴ = 660522007 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (660538397) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330269195 + 330269196.

It is an arithmetic number, because the mean of its divisors is an integer number (330269196).

Almost surely, 2^660538391 is an apocalyptic number.

660538391 is a deficient number, since it is larger than the sum of its proper divisors (1).

660538391 is an equidigital number, since it uses as much as digits as its factorization.

660538391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 116640, while the sum is 41.

The square root of 660538391 is about 25700.9414419005. The cubic root of 660538391 is about 870.8954496435.

The spelling of 660538391 in words is "six hundred sixty million, five hundred thirty-eight thousand, three hundred ninety-one".