81389611607040 has 2816 divisors, whose sum is σ = 332159485870080. Its totient is φ = 19120211066880.

The previous prime is 81389611607011. The next prime is 81389611607047. The reversal of 81389611607040 is 4070611698318.

81389611607040 is a `hidden beast` number, since 8 + 1 + 389 + 61 + 160 + 7 + 0 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (2816).

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 (81389611607047) by changing a digit.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 640863083457 + ... + 640863083583.

It is an arithmetic number, because the mean of its divisors is an integer number (117954362880).

Almost surely, 2^{81389611607040} is an apocalyptic number.

81389611607040 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 81389611607040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (166079742935040).

81389611607040 is an abundant number, since it is smaller than the sum of its proper divisors (250769874263040).

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

81389611607040 is an equidigital number, since it uses as much as digits as its factorization.

81389611607040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 249 (or 191 counting only the distinct ones).

The product of its (nonzero) digits is 1741824, while the sum is 54.

The spelling of 81389611607040 in words is "eighty-one trillion, three hundred eighty-nine billion, six hundred eleven million, six hundred seven thousand, forty".