81291881250 has 144 divisors (see below), whose sum is σ = 227257954560. Its totient is φ = 20978100000.

The previous prime is 81291881233. The next prime is 81291881267. The reversal of 81291881250 is 5218819218.

It is an interprime number because it is at equal distance from previous prime (81291881233) and next prime (81291881267).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a junction number, because it is equal to n+sod(n) for n = 81291881196 and 81291881205.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1720441 + ... + 1767059.

It is an arithmetic number, because the mean of its divisors is an integer number (1578180240).

Almost surely, 2^81291881250 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81291881250, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (113628977280).

81291881250 is an abundant number, since it is smaller than the sum of its proper divisors (145966073310).

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

81291881250 is a wasteful number, since it uses less digits than its factorization.

81291881250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46683 (or 46660 counting only the distinct ones).

The product of its (nonzero) digits is 92160, while the sum is 45.

The spelling of 81291881250 in words is "eighty-one billion, two hundred ninety-one million, eight hundred eighty-one thousand, two hundred fifty".