81444447 has 30 divisors (see below), whose sum is σ = 139412328. Its totient is φ = 46416888.

The previous prime is 81444439. The next prime is 81444479. The reversal of 81444447 is 74444418.

It is not a de Polignac number, because 81444447 - 2³ = 81444439 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81444547) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 214704 + ... + 215082.

Almost surely, 2^81444447 is an apocalyptic number.

81444447 is a deficient number, since it is larger than the sum of its proper divisors (57967881).

81444447 is an frugal number, since it uses more digits than its factorization.

81444447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 777 (or 389 counting only the distinct ones).

The product of its digits is 57344, while the sum is 36.

The square root of 81444447 is about 9024.6577220413. The cubic root of 81444447 is about 433.4647904258.

The spelling of 81444447 in words is "eighty-one million, four hundred forty-four thousand, four hundred forty-seven".