81618489810 has 1024 divisors, whose sum is σ = 288291225600. Its totient is φ = 16124313600.

The previous prime is 81618489803. The next prime is 81618489851. The reversal of 81618489810 is 1898481618.

It is a happy number.

81618489810 is a `hidden beast` number, since 8 + 1 + 618 + 4 + 8 + 9 + 8 + 10 = 666.

It is a super-2 number, since 2×81618489810² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 511 ways as a sum of consecutive naturals, for example, 841427682 + ... + 841427778.

It is an arithmetic number, because the mean of its divisors is an integer number (281534400).

Almost surely, 2^81618489810 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81618489810, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (144145612800).

81618489810 is an abundant number, since it is smaller than the sum of its proper divisors (206672735790).

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

81618489810 is a wasteful number, since it uses less digits than its factorization.

81618489810 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 224 (or 218 counting only the distinct ones).

The product of its (nonzero) digits is 884736, while the sum is 54.

The spelling of 81618489810 in words is "eighty-one billion, six hundred eighteen million, four hundred eighty-nine thousand, eight hundred ten".