81579136240 has 480 divisors, whose sum is σ = 244581524352. Its totient is φ = 24684134400.

The previous prime is 81579136237. The next prime is 81579136259. The reversal of 81579136240 is 4263197518.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 338502520 + ... + 338502760.

It is a 1-persistent number, because it is pandigital, but 2⋅81579136240 = 163158272480 is not.

Almost surely, 2^81579136240 is an apocalyptic number.

81579136240 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 81579136240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (122290762176).

81579136240 is an abundant number, since it is smaller than the sum of its proper divisors (163002388112).

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

81579136240 is a wasteful number, since it uses less digits than its factorization.

81579136240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 377 (or 340 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 46.

The spelling of 81579136240 in words is "eighty-one billion, five hundred seventy-nine million, one hundred thirty-six thousand, two hundred forty".