81777689616 has 40 divisors (see below), whose sum is σ = 241438894144. Its totient is φ = 23365054080.

The previous prime is 81777689569. The next prime is 81777689641. The reversal of 81777689616 is 61698677718.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 121692655 + ... + 121693326.

Almost surely, 2^81777689616 is an apocalyptic number.

It is an amenable number.

81777689616 is an abundant number, since it is smaller than the sum of its proper divisors (159661204528).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81777689616 is a wasteful number, since it uses less digits than its factorization.

81777689616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 243385999 (or 243385993 counting only the distinct ones).

The product of its digits is 42674688, while the sum is 66.

The spelling of 81777689616 in words is "eighty-one billion, seven hundred seventy-seven million, six hundred eighty-nine thousand, six hundred sixteen".