81544913 has 8 divisors (see below), whose sum is σ = 85321728. Its totient is φ = 77787424.

The previous prime is 81544909. The next prime is 81544919. The reversal of 81544913 is 31944518.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81544913 - 2² = 81544909 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81544919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4181 + ... + 13437.

It is an arithmetic number, because the mean of its divisors is an integer number (10665216).

Almost surely, 2^81544913 is an apocalyptic number.

It is an amenable number.

81544913 is a deficient number, since it is larger than the sum of its proper divisors (3776815).

81544913 is a wasteful number, since it uses less digits than its factorization.

81544913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9663.

The product of its digits is 17280, while the sum is 35.

The square root of 81544913 is about 9030.2222010314. Note that the first 4 decimals coincide. The cubic root of 81544913 is about 433.6429510456.

The spelling of 81544913 in words is "eighty-one million, five hundred forty-four thousand, nine hundred thirteen".