81491136071 has 8 divisors (see below), whose sum is σ = 83338785024. Its totient is φ = 79662056760.

The previous prime is 81491136053. The next prime is 81491136113. The reversal of 81491136071 is 17063119418.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81491136071 - 2⁶ = 81491136007 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81491132071) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4633535 + ... + 4651088.

It is an arithmetic number, because the mean of its divisors is an integer number (10417348128).

Almost surely, 2^81491136071 is an apocalyptic number.

81491136071 is a deficient number, since it is larger than the sum of its proper divisors (1847648953).

81491136071 is a wasteful number, since it uses less digits than its factorization.

81491136071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9284821.

The product of its (nonzero) digits is 36288, while the sum is 41.

The spelling of 81491136071 in words is "eighty-one billion, four hundred ninety-one million, one hundred thirty-six thousand, seventy-one".