81473091840 has 1440 divisors, whose sum is σ = 356146560000. Its totient is φ = 17752670208.

The previous prime is 81473091829. The next prime is 81473091851. The reversal of 81473091840 is 4819037418.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81473091829) and next prime (81473091851).

It is a tau number, because it is divible by the number of its divisors (1440).

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

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 1031304921 + ... + 1031304999.

It is an arithmetic number, because the mean of its divisors is an integer number (247324000).

Almost surely, 2^81473091840 is an apocalyptic number.

81473091840 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 81473091840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (178073280000).

81473091840 is an abundant number, since it is smaller than the sum of its proper divisors (274673468160).

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

81473091840 is an equidigital number, since it uses as much as digits as its factorization.

81473091840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 162 (or 125 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 45.

The spelling of 81473091840 in words is "eighty-one billion, four hundred seventy-three million, ninety-one thousand, eight hundred forty".