505499997991 has 2 divisors, whose sum is σ = 505499997992. Its totient is φ = 505499997990.

The previous prime is 505499997953. The next prime is 505499997997. The reversal of 505499997991 is 199799994505.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 505499997991 - 2⁹ = 505499997479 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (505499997997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 252749998995 + 252749998996.

It is an arithmetic number, because the mean of its divisors is an integer number (252749998996).

Almost surely, 2^505499997991 is an apocalyptic number.

505499997991 is a deficient number, since it is larger than the sum of its proper divisors (1).

505499997991 is an equidigital number, since it uses as much as digits as its factorization.

505499997991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 372008700, while the sum is 76.

The spelling of 505499997991 in words is "five hundred five billion, four hundred ninety-nine million, nine hundred ninety-seven thousand, nine hundred ninety-one".