81426978791424 has 1680 divisors, whose sum is σ = 292336915147200. Its totient is φ = 22506484137984.

The previous prime is 81426978791387. The next prime is 81426978791437. The reversal of 81426978791424 is 42419787962418.

81426978791424 is a `hidden beast` number, since 8 + 1 + 4 + 2 + 69 + 78 + 79 + 1 + 424 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 194336464687 + ... + 194336465105.

It is an arithmetic number, because the mean of its divisors is an integer number (174010068540).

Almost surely, 2^{81426978791424} is an apocalyptic number.

81426978791424 is a gapful number since it is divisible by the number (84) 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 81426978791424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (146168457573600).

81426978791424 is an abundant number, since it is smaller than the sum of its proper divisors (210909936355776).

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

81426978791424 is a wasteful number, since it uses less digits than its factorization.

81426978791424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 653 (or 613 counting only the distinct ones).

The product of its digits is 390168576, while the sum is 72.

The spelling of 81426978791424 in words is "eighty-one trillion, four hundred twenty-six billion, nine hundred seventy-eight million, seven hundred ninety-one thousand, four hundred twenty-four".