81227473920 has 264 divisors, whose sum is σ = 291879666624. Its totient is φ = 21660327936.

The previous prime is 81227473909. The next prime is 81227473927. The reversal of 81227473920 is 2937472218.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (81227473927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1211517 + ... + 1276803.

Almost surely, 2^81227473920 is an apocalyptic number.

81227473920 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 81227473920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (145939833312).

81227473920 is an abundant number, since it is smaller than the sum of its proper divisors (210652192704).

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

81227473920 is an equidigital number, since it uses as much as digits as its factorization.

81227473920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65327 (or 65297 counting only the distinct ones).

The product of its (nonzero) digits is 338688, while the sum is 45.

The spelling of 81227473920 in words is "eighty-one billion, two hundred twenty-seven million, four hundred seventy-three thousand, nine hundred twenty".