81351577500 has 120 divisors (see below), whose sum is σ = 238328310528. Its totient is φ = 21590520000.

The previous prime is 81351577499. The next prime is 81351577511. The reversal of 81351577500 is 577515318.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 1556797 + ... + 1608203.

Almost surely, 2^81351577500 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 81351577500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (119164155264).

81351577500 is an abundant number, since it is smaller than the sum of its proper divisors (156976733028).

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

81351577500 is a wasteful number, since it uses less digits than its factorization.

81351577500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51645 (or 51628 counting only the distinct ones).

The product of its (nonzero) digits is 147000, while the sum is 42.

The spelling of 81351577500 in words is "eighty-one billion, three hundred fifty-one million, five hundred seventy-seven thousand, five hundred".