660063991 has 2 divisors, whose sum is σ = 660063992. Its totient is φ = 660063990.

The previous prime is 660063941. The next prime is 660064003. The reversal of 660063991 is 199360066.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 660063991 - 2⁷ = 660063863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (660063941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330031995 + 330031996.

It is an arithmetic number, because the mean of its divisors is an integer number (330031996).

Almost surely, 2^660063991 is an apocalyptic number.

660063991 is a deficient number, since it is larger than the sum of its proper divisors (1).

660063991 is an equidigital number, since it uses as much as digits as its factorization.

660063991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 52488, while the sum is 40.

The square root of 660063991 is about 25691.7105502923. The cubic root of 660063991 is about 870.6869067561.

The spelling of 660063991 in words is "six hundred sixty million, sixty-three thousand, nine hundred ninety-one".