81581902500 has 480 divisors, whose sum is σ = 281444308992. Its totient is φ = 18000000000.

The previous prime is 81581902439. The next prime is 81581902547. The reversal of 81581902500 is 520918518.

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 325027375 + ... + 325027625.

Almost surely, 2^81581902500 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 81581902500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (140722154496).

81581902500 is an abundant number, since it is smaller than the sum of its proper divisors (199862406492).

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

81581902500 is a wasteful number, since it uses less digits than its factorization.

81581902500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 477 (or 460 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 39.

The spelling of 81581902500 in words is "eighty-one billion, five hundred eighty-one million, nine hundred two thousand, five hundred".