11661721344 has 216 divisors, whose sum is σ = 41383657952. Its totient is φ = 3075563520.

The previous prime is 11661721343. The next prime is 11661721363. The reversal of 11661721344 is 44312716611.

11661721344 is a `hidden beast` number, since 1 + 1 + 6 + 617 + 2 + 1 + 34 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 11661721299 and 11661721308.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11661721343) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 181854 + ... + 237474.

Almost surely, 2^11661721344 is an apocalyptic number.

11661721344 is a gapful number since it is divisible by the number (14) 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 11661721344, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20691828976).

11661721344 is an abundant number, since it is smaller than the sum of its proper divisors (29721936608).

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

11661721344 is a wasteful number, since it uses less digits than its factorization.

11661721344 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55663 (or 55646 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The spelling of 11661721344 in words is "eleven billion, six hundred sixty-one million, seven hundred twenty-one thousand, three hundred forty-four".