81161542385 has 32 divisors (see below), whose sum is σ = 121490095104. Its totient is φ = 50567544000.

The previous prime is 81161542379. The next prime is 81161542403. The reversal of 81161542385 is 58324516118.

It is not a de Polignac number, because 81161542385 - 2²² = 81157348081 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 688850 + ... + 798020.

It is an arithmetic number, because the mean of its divisors is an integer number (3796565472).

Almost surely, 2^81161542385 is an apocalyptic number.

It is an amenable number.

81161542385 is a deficient number, since it is larger than the sum of its proper divisors (40328552719).

81161542385 is a wasteful number, since it uses less digits than its factorization.

81161542385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111125.

The product of its digits is 230400, while the sum is 44.

The spelling of 81161542385 in words is "eighty-one billion, one hundred sixty-one million, five hundred forty-two thousand, three hundred eighty-five".