81493120899 has 32 divisors (see below), whose sum is σ = 123094664000. Its totient is φ = 53275180032.

The previous prime is 81493120889. The next prime is 81493120903. The reversal of 81493120899 is 99802139418.

It is a Cunningham number, because it is equal to 285470²-1.

It is not a de Polignac number, because 81493120899 - 2⁵ = 81493120867 is a prime.

It is a super-2 number, since 2×81493120899² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81493120889) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 142737 + ... + 428205.

It is an arithmetic number, because the mean of its divisors is an integer number (3846708250).

Almost surely, 2^81493120899 is an apocalyptic number.

81493120899 is a deficient number, since it is larger than the sum of its proper divisors (41601543101).

81493120899 is a wasteful number, since it uses less digits than its factorization.

81493120899 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 285684 (or 285678 counting only the distinct ones).

The product of its (nonzero) digits is 1119744, while the sum is 54.

The spelling of 81493120899 in words is "eighty-one billion, four hundred ninety-three million, one hundred twenty thousand, eight hundred ninety-nine".