81447911 has 4 divisors (see below), whose sum is σ = 81626592. Its totient is φ = 81269232.

The previous prime is 81447887. The next prime is 81447913. The reversal of 81447911 is 11974418.

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

It is a cyclic number.

It is not a de Polignac number, because 81447911 - 2¹⁴ = 81431527 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 (81447913) 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, 88655 + ... + 89568.

It is an arithmetic number, because the mean of its divisors is an integer number (20406648).

Almost surely, 2^81447911 is an apocalyptic number.

81447911 is a deficient number, since it is larger than the sum of its proper divisors (178681).

81447911 is a wasteful number, since it uses less digits than its factorization.

81447911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 178680.

The product of its digits is 8064, while the sum is 35.

The square root of 81447911 is about 9024.8496386366. The cubic root of 81447911 is about 433.4709357220.

The spelling of 81447911 in words is "eighty-one million, four hundred forty-seven thousand, nine hundred eleven".