81489647 has 2 divisors, whose sum is σ = 81489648. Its totient is φ = 81489646.

The previous prime is 81489643. The next prime is 81489691. The reversal of 81489647 is 74698418.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81489647 - 2² = 81489643 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81489643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40744823 + 40744824.

It is an arithmetic number, because the mean of its divisors is an integer number (40744824).

Almost surely, 2^81489647 is an apocalyptic number.

81489647 is a deficient number, since it is larger than the sum of its proper divisors (1).

81489647 is an equidigital number, since it uses as much as digits as its factorization.

81489647 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 387072, while the sum is 47.

The square root of 81489647 is about 9027.1616247855. The cubic root of 81489647 is about 433.5449636231.

The spelling of 81489647 in words is "eighty-one million, four hundred eighty-nine thousand, six hundred forty-seven".