81447071 has 4 divisors (see below), whose sum is σ = 84988272. Its totient is φ = 77905872.

The previous prime is 81447029. The next prime is 81447073. The reversal of 81447071 is 17074418.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81447071 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 (81447073) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1770566 + ... + 1770611.

It is an arithmetic number, because the mean of its divisors is an integer number (21247068).

Almost surely, 2^81447071 is an apocalyptic number.

81447071 is a deficient number, since it is larger than the sum of its proper divisors (3541201).

81447071 is a wasteful number, since it uses less digits than its factorization.

81447071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3541200.

The product of its (nonzero) digits is 6272, while the sum is 32.

The square root of 81447071 is about 9024.8031003452. The cubic root of 81447071 is about 433.4694455392.

The spelling of 81447071 in words is "eighty-one million, four hundred forty-seven thousand, seventy-one".