81851867000 has 256 divisors, whose sum is σ = 208039104000. Its totient is φ = 30040704000.

The previous prime is 81851866991. The next prime is 81851867003. The reversal of 81851867000 is 76815818.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81851867003) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 139440707 + ... + 139441293.

It is an arithmetic number, because the mean of its divisors is an integer number (812652750).

Almost surely, 2^81851867000 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 81851867000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104019552000).

81851867000 is an abundant number, since it is smaller than the sum of its proper divisors (126187237000).

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

81851867000 is a wasteful number, since it uses less digits than its factorization.

81851867000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 847 (or 833 counting only the distinct ones).

The product of its (nonzero) digits is 107520, while the sum is 44.

The spelling of 81851867000 in words is "eighty-one billion, eight hundred fifty-one million, eight hundred sixty-seven thousand".