81975728080 has 40 divisors (see below), whose sum is σ = 193823978400. Its totient is φ = 32234521728.

The previous prime is 81975728039. The next prime is 81975728089. The reversal of 81975728080 is 8082757918.

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-2 number, since 2×81975728080² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81975728089) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8679150 + ... + 8688589.

It is an arithmetic number, because the mean of its divisors is an integer number (4845599460).

Almost surely, 2^81975728080 is an apocalyptic number.

81975728080 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81975728080 is an abundant number, since it is smaller than the sum of its proper divisors (111848250320).

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

81975728080 is a wasteful number, since it uses less digits than its factorization.

81975728080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17367811 (or 17367805 counting only the distinct ones).

The product of its (nonzero) digits is 2257920, while the sum is 55.

The spelling of 81975728080 in words is "eighty-one billion, nine hundred seventy-five million, seven hundred twenty-eight thousand, eighty".