81017035920 has 280 divisors, whose sum is σ = 285079093056. Its totient is φ = 21400982784.

The previous prime is 81017035919. The next prime is 81017035927. The reversal of 81017035920 is 2953071018.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (81017035927) by changing a digit.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 6233749 + ... + 6246731.

Almost surely, 2^81017035920 is an apocalyptic number.

81017035920 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81017035920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (142539546528).

81017035920 is an abundant number, since it is smaller than the sum of its proper divisors (204062057136).

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

81017035920 is a wasteful number, since it uses less digits than its factorization.

81017035920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13121 (or 13100 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 36.

The spelling of 81017035920 in words is "eighty-one billion, seventeen million, thirty-five thousand, nine hundred twenty".