81900560800 has 144 divisors (see below), whose sum is σ = 204262598232. Its totient is φ = 32055296000.

The previous prime is 81900560767. The next prime is 81900560809. The reversal of 81900560800 is 806500918.

It can be written as a sum of positive squares in 12 ways, for example, as 16710215824 + 65190344976 = 129268^2 + 255324^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81900560800.

It is not an unprimeable number, because it can be changed into a prime (81900560809) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16999992 + ... + 17004808.

Almost surely, 2^81900560800 is an apocalyptic number.

81900560800 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 81900560800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (102131299116).

81900560800 is an abundant number, since it is smaller than the sum of its proper divisors (122362037432).

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

81900560800 is a wasteful number, since it uses less digits than its factorization.

81900560800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5291 (or 5278 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 37.

The spelling of 81900560800 in words is "eighty-one billion, nine hundred million, five hundred sixty thousand, eight hundred".