81349691040 has 384 divisors, whose sum is σ = 301411756800. Its totient is φ = 20456755200.

The previous prime is 81349691039. The next prime is 81349691113. The reversal of 81349691040 is 4019694318.

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 63 ways as a sum of consecutive naturals, for example, 5379490 + ... + 5394590.

It is an arithmetic number, because the mean of its divisors is an integer number (784926450).

Almost surely, 2^81349691040 is an apocalyptic number.

81349691040 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 81349691040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (150705878400).

81349691040 is an abundant number, since it is smaller than the sum of its proper divisors (220062065760).

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

81349691040 is a wasteful number, since it uses less digits than its factorization.

81349691040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15197 (or 15183 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 45.

The spelling of 81349691040 in words is "eighty-one billion, three hundred forty-nine million, six hundred ninety-one thousand, forty".