81329047 has 2 divisors, whose sum is σ = 81329048. Its totient is φ = 81329046.

The previous prime is 81329029. The next prime is 81329069. The reversal of 81329047 is 74092318.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81329047 is a prime.

It is a super-2 number, since 2×81329047² = 13228827771856418, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81329077) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40664523 + 40664524.

It is an arithmetic number, because the mean of its divisors is an integer number (40664524).

Almost surely, 2^81329047 is an apocalyptic number.

81329047 is a deficient number, since it is larger than the sum of its proper divisors (1).

81329047 is an equidigital number, since it uses as much as digits as its factorization.

81329047 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 81329047 is about 9018.2618613567. The cubic root of 81329047 is about 433.2599658169.

The spelling of 81329047 in words is "eighty-one million, three hundred twenty-nine thousand, forty-seven".