81241187840 has 80 divisors (see below), whose sum is σ = 194858421120. Its totient is φ = 32484802560.

The previous prime is 81241187837. The next prime is 81241187869. The reversal of 81241187840 is 4878114218.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a junction number, because it is equal to n+sod(n) for n = 81241187791 and 81241187800.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12364076 + ... + 12370644.

It is an arithmetic number, because the mean of its divisors is an integer number (2435730264).

Almost surely, 2^81241187840 is an apocalyptic number.

81241187840 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81241187840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (97429210560).

81241187840 is an abundant number, since it is smaller than the sum of its proper divisors (113617233280).

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

81241187840 is an equidigital number, since it uses as much as digits as its factorization.

81241187840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11423 (or 11407 counting only the distinct ones).

The product of its (nonzero) digits is 114688, while the sum is 44.

The spelling of 81241187840 in words is "eighty-one billion, two hundred forty-one million, one hundred eighty-seven thousand, eight hundred forty".