81677916773 has 4 divisors (see below), whose sum is σ = 81798564300. Its totient is φ = 81557269248.

The previous prime is 81677916739. The next prime is 81677916787. The reversal of 81677916773 is 37761977618.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 55259315329 + 26418601444 = 235073^2 + 162538^2 .

It is a cyclic number.

It is not a de Polignac number, because 81677916773 - 2¹⁴ = 81677900389 is a prime.

It is a super-2 number, since 2×81677916773² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81677916373) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 60322748 + ... + 60324101.

It is an arithmetic number, because the mean of its divisors is an integer number (20449641075).

Almost surely, 2^81677916773 is an apocalyptic number.

It is an amenable number.

81677916773 is a deficient number, since it is larger than the sum of its proper divisors (120647527).

81677916773 is a wasteful number, since it uses less digits than its factorization.

81677916773 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120647526.

The product of its digits is 18670176, while the sum is 62.

The spelling of 81677916773 in words is "eighty-one billion, six hundred seventy-seven million, nine hundred sixteen thousand, seven hundred seventy-three".