81944567 has 4 divisors (see below), whose sum is σ = 82981920. Its totient is φ = 80907216.

The previous prime is 81944557. The next prime is 81944623. The reversal of 81944567 is 76544918.

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 81944567 - 2¹⁴ = 81928183 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 (81944507) 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, 518558 + ... + 518715.

It is an arithmetic number, because the mean of its divisors is an integer number (20745480).

Almost surely, 2^81944567 is an apocalyptic number.

81944567 is a deficient number, since it is larger than the sum of its proper divisors (1037353).

81944567 is a wasteful number, since it uses less digits than its factorization.

81944567 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1037352.

The product of its digits is 241920, while the sum is 44.

The square root of 81944567 is about 9052.3238452897. The cubic root of 81944567 is about 434.3502290931.

The spelling of 81944567 in words is "eighty-one million, nine hundred forty-four thousand, five hundred sixty-seven".