81554278549 has 16 divisors (see below), whose sum is σ = 84658268160. Its totient is φ = 78480823680.

The previous prime is 81554278543. The next prime is 81554278571. The reversal of 81554278549 is 94587245518.

It is a cyclic number.

It is not a de Polignac number, because 81554278549 - 2³ = 81554278541 is a prime.

It is a super-2 number, since 2×81554278549² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81554278493 and 81554278502.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81554278541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5423289 + ... + 5438305.

It is an arithmetic number, because the mean of its divisors is an integer number (5291141760).

Almost surely, 2^81554278549 is an apocalyptic number.

It is an amenable number.

81554278549 is a deficient number, since it is larger than the sum of its proper divisors (3103989611).

81554278549 is a wasteful number, since it uses less digits than its factorization.

81554278549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16020.

The product of its digits is 16128000, while the sum is 58.

The spelling of 81554278549 in words is "eighty-one billion, five hundred fifty-four million, two hundred seventy-eight thousand, five hundred forty-nine".