81575506657 has 8 divisors (see below), whose sum is σ = 85344528384. Its totient is φ = 77825006688.

The previous prime is 81575506643. The next prime is 81575506669. The reversal of 81575506657 is 75660557518.

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 81575506657 - 2¹⁹ = 81574982369 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81575506598 and 81575506607.

It is not an unprimeable number, because it can be changed into a prime (81575506697) 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, 4621428 + ... + 4639045.

It is an arithmetic number, because the mean of its divisors is an integer number (10668066048).

Almost surely, 2^81575506657 is an apocalyptic number.

It is an amenable number.

81575506657 is a deficient number, since it is larger than the sum of its proper divisors (3769021727).

81575506657 is a wasteful number, since it uses less digits than its factorization.

81575506657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9260879.

The product of its (nonzero) digits is 8820000, while the sum is 55.

The spelling of 81575506657 in words is "eighty-one billion, five hundred seventy-five million, five hundred six thousand, six hundred fifty-seven".