81387911388780 has 144 divisors (see below), whose sum is σ = 275156654179680. Its totient is φ = 19351676749824.

The previous prime is 81387911388779. The next prime is 81387911388841. The reversal of 81387911388780 is 8788311978318.

81387911388780 is a `hidden beast` number, since 8 + 1 + 3 + 87 + 91 + 1 + 388 + 7 + 80 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 81387911388699 and 81387911388708.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 699872299 + ... + 699988578.

It is an arithmetic number, because the mean of its divisors is an integer number (1910810098470).

Almost surely, 2^{81387911388780} is an apocalyptic number.

It is an amenable number.

81387911388780 is an abundant number, since it is smaller than the sum of its proper divisors (193768742790900).

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

81387911388780 is a wasteful number, since it uses less digits than its factorization.

81387911388780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1399860928 (or 1399860923 counting only the distinct ones).

The product of its (nonzero) digits is 130056192, while the sum is 72.

The spelling of 81387911388780 in words is "eighty-one trillion, three hundred eighty-seven billion, nine hundred eleven million, three hundred eighty-eight thousand, seven hundred eighty".