81971457863 has 2 divisors, whose sum is σ = 81971457864. Its totient is φ = 81971457862.

The previous prime is 81971457823. The next prime is 81971457877. The reversal of 81971457863 is 36875417918.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81971457863 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81971457823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40985728931 + 40985728932.

It is an arithmetic number, because the mean of its divisors is an integer number (40985728932).

Almost surely, 2^81971457863 is an apocalyptic number.

81971457863 is a deficient number, since it is larger than the sum of its proper divisors (1).

81971457863 is an equidigital number, since it uses as much as digits as its factorization.

81971457863 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10160640, while the sum is 59.

The spelling of 81971457863 in words is "eighty-one billion, nine hundred seventy-one million, four hundred fifty-seven thousand, eight hundred sixty-three".