81329149440 has 1920 divisors, whose sum is σ = 382893350400. Its totient is φ = 16164126720.

The previous prime is 81329149417. The next prime is 81329149453. The reversal of 81329149440 is 4494192318.

81329149440 is a `hidden beast` number, since 8 + 1 + 32 + 91 + 494 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (1920).

It is a super-2 number, since 2×81329149440² (a number of 23 digits) contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 1378460131 + ... + 1378460189.

It is an arithmetic number, because the mean of its divisors is an integer number (199423620).

Almost surely, 2^81329149440 is an apocalyptic number.

81329149440 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 81329149440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (191446675200).

81329149440 is an abundant number, since it is smaller than the sum of its proper divisors (301564200960).

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

81329149440 is a wasteful number, since it uses less digits than its factorization.

81329149440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153 (or 124 counting only the distinct ones).

The product of its (nonzero) digits is 248832, while the sum is 45.

The spelling of 81329149440 in words is "eighty-one billion, three hundred twenty-nine million, one hundred forty-nine thousand, four hundred forty".