81355679424 has 560 divisors, whose sum is σ = 260695622880. Its totient is φ = 25035816960.

The previous prime is 81355679423. The next prime is 81355679429. The reversal of 81355679424 is 42497655318.

It is a happy number.

81355679424 is a `hidden beast` number, since 8 + 1 + 35 + 567 + 9 + 42 + 4 = 666.

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

It is not an unprimeable number, because it can be changed into a prime (81355679423) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 412972894 + ... + 412973090.

It is an arithmetic number, because the mean of its divisors is an integer number (465527898).

Almost surely, 2^81355679424 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 81355679424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130347811440).

81355679424 is an abundant number, since it is smaller than the sum of its proper divisors (179339943456).

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

81355679424 is a wasteful number, since it uses less digits than its factorization.

81355679424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 358 (or 339 counting only the distinct ones).

The product of its digits is 7257600, while the sum is 54.

The spelling of 81355679424 in words is "eighty-one billion, three hundred fifty-five million, six hundred seventy-nine thousand, four hundred twenty-four".