81539047 has 2 divisors, whose sum is σ = 81539048. Its totient is φ = 81539046.

The previous prime is 81539033. The next prime is 81539063. The reversal of 81539047 is 74093518.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81539047 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81538997 and 81539015.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81539147) 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, 40769523 + 40769524.

It is an arithmetic number, because the mean of its divisors is an integer number (40769524).

Almost surely, 2^81539047 is an apocalyptic number.

81539047 is a deficient number, since it is larger than the sum of its proper divisors (1).

81539047 is an equidigital number, since it uses as much as digits as its factorization.

81539047 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 30240, while the sum is 37.

The square root of 81539047 is about 9029.8973969808. The cubic root of 81539047 is about 433.6325526428.

The spelling of 81539047 in words is "eighty-one million, five hundred thirty-nine thousand, forty-seven".