81385958500 has 768 divisors, whose sum is σ = 249852395520. Its totient is φ = 22394880000.

The previous prime is 81385958471. The next prime is 81385958543. The reversal of 81385958500 is 585958318.

It is an unprimeable number.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 839030452 + ... + 839030548.

It is an arithmetic number, because the mean of its divisors is an integer number (325328640).

Almost surely, 2^81385958500 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81385958500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (124926197760).

81385958500 is an abundant number, since it is smaller than the sum of its proper divisors (168466437020).

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

81385958500 is a wasteful number, since it uses less digits than its factorization.

81385958500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221 (or 209 counting only the distinct ones).

The product of its (nonzero) digits is 1728000, while the sum is 52.

The spelling of 81385958500 in words is "eighty-one billion, three hundred eighty-five million, nine hundred fifty-eight thousand, five hundred".