81839306545920 has 1728 divisors, whose sum is σ = 359488804147200. Its totient is φ = 16696348508160.

The previous prime is 81839306545837. The next prime is 81839306545939. The reversal of 81839306545920 is 2954560393818.

81839306545920 is a `hidden beast` number, since 8 + 1 + 8 + 3 + 9 + 30 + 6 + 5 + 4 + 592 + 0 = 666.

It is a super-3 number, since 3×81839306545920³ (a number of 43 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

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

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 14828644921 + ... + 14828650439.

It is an arithmetic number, because the mean of its divisors is an integer number (208037502400).

Almost surely, 2^{81839306545920} is an apocalyptic number.

81839306545920 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81839306545920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (179744402073600).

81839306545920 is an abundant number, since it is smaller than the sum of its proper divisors (277649497601280).

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

81839306545920 is a wasteful number, since it uses less digits than its factorization.

81839306545920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5866 (or 5849 counting only the distinct ones).

The product of its (nonzero) digits is 55987200, while the sum is 63.

The spelling of 81839306545920 in words is "eighty-one trillion, eight hundred thirty-nine billion, three hundred six million, five hundred forty-five thousand, nine hundred twenty".