81553549820 has 12 divisors (see below), whose sum is σ = 171262454664. Its totient is φ = 32621419920.

The previous prime is 81553549769. The next prime is 81553549853. The reversal of 81553549820 is 2894535518.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2038838726 + ... + 2038838765.

It is an arithmetic number, because the mean of its divisors is an integer number (14271871222).

Almost surely, 2^81553549820 is an apocalyptic number.

It is an amenable number.

81553549820 is an abundant number, since it is smaller than the sum of its proper divisors (89708904844).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81553549820 is a wasteful number, since it uses less digits than its factorization.

81553549820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4077677500 (or 4077677498 counting only the distinct ones).

The product of its (nonzero) digits is 1728000, while the sum is 50.

It can be divided in two parts, 815535498 and 20, that added together give a palindrome (815535518).

The spelling of 81553549820 in words is "eighty-one billion, five hundred fifty-three million, five hundred forty-nine thousand, eight hundred twenty".