81971699 has 2 divisors, whose sum is σ = 81971700. Its totient is φ = 81971698.

The previous prime is 81971683. The next prime is 81971723. The reversal of 81971699 is 99617918.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81971699 - 2⁴ = 81971683 is a prime.

It is not a weakly prime, because it can be changed into another prime (81971629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40985849 + 40985850.

It is an arithmetic number, because the mean of its divisors is an integer number (40985850).

Almost surely, 2^81971699 is an apocalyptic number.

81971699 is a deficient number, since it is larger than the sum of its proper divisors (1).

81971699 is an equidigital number, since it uses as much as digits as its factorization.

81971699 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 244944, while the sum is 50.

The square root of 81971699 is about 9053.8223419725. The cubic root of 81971699 is about 434.3981618621.

The spelling of 81971699 in words is "eighty-one million, nine hundred seventy-one thousand, six hundred ninety-nine".