81993017 has 2 divisors, whose sum is σ = 81993018. Its totient is φ = 81993016.

The previous prime is 81993011. The next prime is 81993029. The reversal of 81993017 is 71039918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 51566761 + 30426256 = 7181^2 + 5516^2 .

It is a cyclic number.

It is not a de Polignac number, because 81993017 - 2¹⁴ = 81976633 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81993011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40996508 + 40996509.

It is an arithmetic number, because the mean of its divisors is an integer number (40996509).

Almost surely, 2^81993017 is an apocalyptic number.

It is an amenable number.

81993017 is a deficient number, since it is larger than the sum of its proper divisors (1).

81993017 is an equidigital number, since it uses as much as digits as its factorization.

81993017 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13608, while the sum is 38.

The square root of 81993017 is about 9054.9995582551. Note that the first 3 decimals coincide. The cubic root of 81993017 is about 434.4358159039.

The spelling of 81993017 in words is "eighty-one million, nine hundred ninety-three thousand, seventeen".