81855498816 has 567 divisors, whose sum is σ = 297812800233. Its totient is φ = 21423467520.

The previous prime is 81855498787. The next prime is 81855498817. The reversal of 81855498816 is 61889455818.

The square root of 81855498816 is 286104.

It is a perfect power (a square), and thus also a powerful number.

81855498816 is a `hidden beast` number, since 8 + 1 + 8 + 5 + 549 + 8 + 81 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 12108801600 + 69746697216 = 110040^2 + 264096^2 .

It is a Harshad number since it is a multiple of its sum of digits (63).

Its product of digits (22118400) is a multiple of the sum of its prime factors (320).

It is not an unprimeable number, because it can be changed into a prime (81855498817) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 624851071 + ... + 624851201.

Almost surely, 2^81855498816 is an apocalyptic number.

81855498816 is the 286104-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81855498816

81855498816 is an abundant number, since it is smaller than the sum of its proper divisors (215957301417).

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

81855498816 is a wasteful number, since it uses less digits than its factorization.

81855498816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320 (or 156 counting only the distinct ones).

The product of its digits is 22118400, while the sum is 63.

The spelling of 81855498816 in words is "eighty-one billion, eight hundred fifty-five million, four hundred ninety-eight thousand, eight hundred sixteen".