81454544640 has 864 divisors, whose sum is σ = 332136395136. Its totient is φ = 18048614400.

The previous prime is 81454544621. The next prime is 81454544657. The reversal of 81454544640 is 4644545418.

81454544640 is a `hidden beast` number, since 8 + 1 + 4 + 545 + 44 + 64 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 594558652 + ... + 594558788.

It is an arithmetic number, because the mean of its divisors is an integer number (384417124).

Almost surely, 2^81454544640 is an apocalyptic number.

81454544640 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 81454544640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (166068197568).

81454544640 is an abundant number, since it is smaller than the sum of its proper divisors (250681850496).

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

81454544640 is a wasteful number, since it uses less digits than its factorization.

81454544640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 345 (or 328 counting only the distinct ones).

The product of its (nonzero) digits is 1228800, while the sum is 45.

The spelling of 81454544640 in words is "eighty-one billion, four hundred fifty-four million, five hundred forty-four thousand, six hundred forty".