81044487551999 has 4 divisors (see below), whose sum is σ = 83658825860160. Its totient is φ = 78430149243840.

The previous prime is 81044487551957. The next prime is 81044487552019. The reversal of 81044487551999 is 99915578444018.

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-81044487551999 is a prime.

It is a super-2 number, since 2×81044487551999² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81044487551299) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1307169154034 + ... + 1307169154095.

It is an arithmetic number, because the mean of its divisors is an integer number (20914706465040).

Almost surely, 2^{81044487551999} is an apocalyptic number.

81044487551999 is a deficient number, since it is larger than the sum of its proper divisors (2614338308161).

81044487551999 is a wasteful number, since it uses less digits than its factorization.

81044487551999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2614338308160.

The product of its (nonzero) digits is 522547200, while the sum is 74.

The spelling of 81044487551999 in words is "eighty-one trillion, forty-four billion, four hundred eighty-seven million, five hundred fifty-one thousand, nine hundred ninety-nine".