81927217 has 2 divisors, whose sum is σ = 81927218. Its totient is φ = 81927216.

The previous prime is 81927193. The next prime is 81927239. The reversal of 81927217 is 71272918.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51279921 + 30647296 = 7161^2 + 5536^2 .

It is a cyclic number.

It is not a de Polignac number, because 81927217 - 2⁷ = 81927089 is a prime.

It is not a weakly prime, because it can be changed into another prime (81927247) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40963608 + 40963609.

It is an arithmetic number, because the mean of its divisors is an integer number (40963609).

Almost surely, 2^81927217 is an apocalyptic number.

It is an amenable number.

81927217 is a deficient number, since it is larger than the sum of its proper divisors (1).

81927217 is an equidigital number, since it uses as much as digits as its factorization.

81927217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14112, while the sum is 37.

The square root of 81927217 is about 9051.3654770979. The cubic root of 81927217 is about 434.3195721556.

The spelling of 81927217 in words is "eighty-one million, nine hundred twenty-seven thousand, two hundred seventeen".