181664778240 has 576 divisors, whose sum is σ = 712401842880. Its totient is φ = 44033310720.

The previous prime is 181664778221. The next prime is 181664778287. The reversal of 181664778240 is 42877466181.

181664778240 is a `hidden beast` number, since 1 + 8 + 166 + 477 + 8 + 2 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (576).

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 47 ways as a sum of consecutive naturals, for example, 27368202 + ... + 27374838.

It is an arithmetic number, because the mean of its divisors is an integer number (1236808755).

Almost surely, 2^181664778240 is an apocalyptic number.

181664778240 is a gapful number since it is divisible by the number (10) 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 181664778240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (356200921440).

181664778240 is an abundant number, since it is smaller than the sum of its proper divisors (530737064640).

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

181664778240 is an equidigital number, since it uses as much as digits as its factorization.

181664778240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6690 (or 6658 counting only the distinct ones).

The product of its (nonzero) digits is 3612672, while the sum is 54.

The spelling of 181664778240 in words is "one hundred eighty-one billion, six hundred sixty-four million, seven hundred seventy-eight thousand, two hundred forty".