81601547555 has 12 divisors (see below), whose sum is σ = 107633116416. Its totient is φ = 59346579600.

The previous prime is 81601547551. The next prime is 81601547591. The reversal of 81601547555 is 55574510618.

It is not a de Polignac number, because 81601547555 - 2² = 81601547551 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81601547551) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 67438691 + ... + 67439900.

It is an arithmetic number, because the mean of its divisors is an integer number (8969426368).

Almost surely, 2^81601547555 is an apocalyptic number.

81601547555 is a deficient number, since it is larger than the sum of its proper divisors (26031568861).

81601547555 is a wasteful number, since it uses less digits than its factorization.

81601547555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134878618 (or 134878607 counting only the distinct ones).

The product of its (nonzero) digits is 840000, while the sum is 47.

The spelling of 81601547555 in words is "eighty-one billion, six hundred one million, five hundred forty-seven thousand, five hundred fifty-five".