81339217 has 2 divisors, whose sum is σ = 81339218. Its totient is φ = 81339216.

The previous prime is 81339199. The next prime is 81339221. The reversal of 81339217 is 71293318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 80120401 + 1218816 = 8951^2 + 1104^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81339217 is a prime.

It is not a weakly prime, because it can be changed into another prime (81339277) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40669608 + 40669609.

It is an arithmetic number, because the mean of its divisors is an integer number (40669609).

Almost surely, 2^81339217 is an apocalyptic number.

It is an amenable number.

81339217 is a deficient number, since it is larger than the sum of its proper divisors (1).

81339217 is an equidigital number, since it uses as much as digits as its factorization.

81339217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9072, while the sum is 34.

The square root of 81339217 is about 9018.8256996130. The cubic root of 81339217 is about 433.2780244333.

The spelling of 81339217 in words is "eighty-one million, three hundred thirty-nine thousand, two hundred seventeen".