81947913600 has 768 divisors, whose sum is σ = 322979328000. Its totient is φ = 18243993600.

The previous prime is 81947913587. The next prime is 81947913611. The reversal of 81947913600 is 631974918.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 81947913600.

It is a congruent number.

It is an unprimeable number.

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 95 ways as a sum of consecutive naturals, for example, 135004497 + ... + 135005103.

It is an arithmetic number, because the mean of its divisors is an integer number (420546000).

Almost surely, 2^81947913600 is an apocalyptic number.

81947913600 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 81947913600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (161489664000).

81947913600 is an abundant number, since it is smaller than the sum of its proper divisors (241031414400).

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

81947913600 is a wasteful number, since it uses less digits than its factorization.

81947913600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 696 (or 665 counting only the distinct ones).

The product of its (nonzero) digits is 326592, while the sum is 48.

The spelling of 81947913600 in words is "eighty-one billion, nine hundred forty-seven million, nine hundred thirteen thousand, six hundred".