81319837040640 has 1240 divisors, whose sum is σ = 336759795587952. Its totient is φ = 18554258718720.

The previous prime is 81319837040609. The next prime is 81319837040737. The reversal of 81319837040640 is 4604073891318.

81319837040640 is a `hidden beast` number, since 8 + 1 + 3 + 198 + 3 + 7 + 0 + 406 + 40 = 666.

It is a super-2 number, since 2×81319837040640² (a number of 29 digits) contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 4783519825912 + ... + 4783519825928.

Almost surely, 2^{81319837040640} is an apocalyptic number.

81319837040640 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 81319837040640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (168379897793976).

81319837040640 is an abundant number, since it is smaller than the sum of its proper divisors (255439958547312).

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

81319837040640 is an frugal number, since it uses more digits than its factorization.

81319837040640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105 (or 38 counting only the distinct ones).

The product of its (nonzero) digits is 3483648, while the sum is 54.

The spelling of 81319837040640 in words is "eighty-one trillion, three hundred nineteen billion, eight hundred thirty-seven million, forty thousand, six hundred forty".