81656028577 has 16 divisors (see below), whose sum is σ = 82599229440. Its totient is φ = 80718739200.

The previous prime is 81656028557. The next prime is 81656028581. The reversal of 81656028577 is 77582065618.

It is a cyclic number.

It is not a de Polignac number, because 81656028577 - 2¹⁹ = 81655504289 is a prime.

It is a super-3 number, since 3×81656028577³ (a number of 34 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81656028557) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 46900927 + ... + 46902667.

It is an arithmetic number, because the mean of its divisors is an integer number (5162451840).

Almost surely, 2^81656028577 is an apocalyptic number.

It is an amenable number.

81656028577 is a deficient number, since it is larger than the sum of its proper divisors (943200863).

81656028577 is a wasteful number, since it uses less digits than its factorization.

81656028577 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3144.

The product of its (nonzero) digits is 5644800, while the sum is 55.

The spelling of 81656028577 in words is "eighty-one billion, six hundred fifty-six million, twenty-eight thousand, five hundred seventy-seven".