81613443840 has 144 divisors (see below), whose sum is σ = 260833106688. Its totient is φ = 21748543488.

The previous prime is 81613443827. The next prime is 81613443871. The reversal of 81613443840 is 4834431618.

It is a junction number, because it is equal to n+sod(n) for n = 81613443792 and 81613443801.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6241149 + ... + 6254211.

Almost surely, 2^81613443840 is an apocalyptic number.

81613443840 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 81613443840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130416553344).

81613443840 is an abundant number, since it is smaller than the sum of its proper divisors (179219662848).

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

81613443840 is a wasteful number, since it uses less digits than its factorization.

81613443840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14714 (or 14700 counting only the distinct ones).

The product of its (nonzero) digits is 221184, while the sum is 42.

The spelling of 81613443840 in words is "eighty-one billion, six hundred thirteen million, four hundred forty-three thousand, eight hundred forty".