81238447 has 4 divisors (see below), whose sum is σ = 81272776. Its totient is φ = 81204120.

The previous prime is 81238439. The next prime is 81238459. The reversal of 81238447 is 74483218.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 74483218 = 2 ⋅37241609.

It is a cyclic number.

It is not a de Polignac number, because 81238447 - 2³ = 81238439 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81238477) 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 in 3 ways as a sum of consecutive naturals, for example, 13329 + ... + 18442.

It is an arithmetic number, because the mean of its divisors is an integer number (20318194).

Almost surely, 2^81238447 is an apocalyptic number.

81238447 is a deficient number, since it is larger than the sum of its proper divisors (34329).

81238447 is a wasteful number, since it uses less digits than its factorization.

81238447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34328.

The product of its digits is 43008, while the sum is 37.

The square root of 81238447 is about 9013.2373207411. The cubic root of 81238447 is about 433.0990231633.

The spelling of 81238447 in words is "eighty-one million, two hundred thirty-eight thousand, four hundred forty-seven".