81521175317 has 8 divisors (see below), whose sum is σ = 82654727424. Its totient is φ = 80388078048.

The previous prime is 81521175313. The next prime is 81521175343. The reversal of 81521175317 is 71357112518.

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 81521175317 - 2² = 81521175313 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 (81521175311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 255518 + ... + 477840.

It is an arithmetic number, because the mean of its divisors is an integer number (10331840928).

Almost surely, 2^81521175317 is an apocalyptic number.

It is an amenable number.

81521175317 is a deficient number, since it is larger than the sum of its proper divisors (1133552107).

81521175317 is a wasteful number, since it uses less digits than its factorization.

81521175317 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 227419.

The product of its digits is 58800, while the sum is 41.

The spelling of 81521175317 in words is "eighty-one billion, five hundred twenty-one million, one hundred seventy-five thousand, three hundred seventeen".