81917447 has 2 divisors, whose sum is σ = 81917448. Its totient is φ = 81917446.

The previous prime is 81917393. The next prime is 81917453. The reversal of 81917447 is 74471918.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81917447 - 2¹⁴ = 81901063 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81917477) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40958723 + 40958724.

It is an arithmetic number, because the mean of its divisors is an integer number (40958724).

Almost surely, 2^81917447 is an apocalyptic number.

81917447 is a deficient number, since it is larger than the sum of its proper divisors (1).

81917447 is an equidigital number, since it uses as much as digits as its factorization.

81917447 is an evil number, because the sum of its binary digits is even.

The product of its digits is 56448, while the sum is 41.

The square root of 81917447 is about 9050.8257634318. The cubic root of 81917447 is about 434.3023069493.

The spelling of 81917447 in words is "eighty-one million, nine hundred seventeen thousand, four hundred forty-seven".