21891366180 has 120 divisors (see below), whose sum is σ = 69096172992. Its totient is φ = 5801813568.

The previous prime is 21891366169. The next prime is 21891366227. The reversal of 21891366180 is 8166319812.

21891366180 is a `hidden beast` number, since 2 + 18 + 9 + 13 + 6 + 618 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 222609 + ... + 305511.

Almost surely, 2^21891366180 is an apocalyptic number.

21891366180 is a gapful number since it is divisible by the number (20) 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 21891366180, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34548086496).

21891366180 is an abundant number, since it is smaller than the sum of its proper divisors (47204806812).

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

21891366180 is a wasteful number, since it uses less digits than its factorization.

21891366180 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83087 (or 83076 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The spelling of 21891366180 in words is "twenty-one billion, eight hundred ninety-one million, three hundred sixty-six thousand, one hundred eighty".