81897840380 has 12 divisors (see below), whose sum is σ = 171985464840. Its totient is φ = 32759136144.

The previous prime is 81897840379. The next prime is 81897840403. The reversal of 81897840380 is 8304879818.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2047445990 + ... + 2047446029.

It is an arithmetic number, because the mean of its divisors is an integer number (14332122070).

Almost surely, 2^81897840380 is an apocalyptic number.

It is an amenable number.

81897840380 is an abundant number, since it is smaller than the sum of its proper divisors (90087624460).

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

81897840380 is a wasteful number, since it uses less digits than its factorization.

81897840380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4094892028 (or 4094892026 counting only the distinct ones).

The product of its (nonzero) digits is 3096576, while the sum is 56.

The spelling of 81897840380 in words is "eighty-one billion, eight hundred ninety-seven million, eight hundred forty thousand, three hundred eighty".