81407794176 has 440 divisors, whose sum is σ = 256326322560. Its totient is φ = 25685434368.

The previous prime is 81407794129. The next prime is 81407794177. The reversal of 81407794176 is 67149770418.

It is a happy number.

81407794176 is a `hidden beast` number, since 81 + 407 + 7 + 94 + 1 + 76 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81407794177) 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 39 ways as a sum of consecutive naturals, for example, 265171815 + ... + 265172121.

It is an arithmetic number, because the mean of its divisors is an integer number (582559824).

Almost surely, 2^81407794176 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81407794176, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128163161280).

81407794176 is an abundant number, since it is smaller than the sum of its proper divisors (174918528384).

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

81407794176 is a wasteful number, since it uses less digits than its factorization.

81407794176 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 501 (or 474 counting only the distinct ones).

The product of its (nonzero) digits is 2370816, while the sum is 54.

The spelling of 81407794176 in words is "eighty-one billion, four hundred seven million, seven hundred ninety-four thousand, one hundred seventy-six".