81771803685 has 48 divisors (see below), whose sum is σ = 166517140608. Its totient is φ = 36597168000.

The previous prime is 81771803681. The next prime is 81771803693. The reversal of 81771803685 is 58630817718.

It is a happy number.

It is not a de Polignac number, because 81771803685 - 2² = 81771803681 is a prime.

It is a super-3 number, since 3×81771803685³ (a number of 34 digits) contains 333 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81771803681) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 6347241 + ... + 6360110.

It is an arithmetic number, because the mean of its divisors is an integer number (3469107096).

Almost surely, 2^81771803685 is an apocalyptic number.

It is an amenable number.

81771803685 is an abundant number, since it is smaller than the sum of its proper divisors (84745336923).

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

81771803685 is a wasteful number, since it uses less digits than its factorization.

81771803685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12707386 (or 12707383 counting only the distinct ones).

The product of its (nonzero) digits is 2257920, while the sum is 54.

The spelling of 81771803685 in words is "eighty-one billion, seven hundred seventy-one million, eight hundred three thousand, six hundred eighty-five".