21894151680 has 360 divisors, whose sum is σ = 77463057672. Its totient is φ = 5714190336.

The previous prime is 21894151619. The next prime is 21894151681. The reversal of 21894151680 is 8615149812.

It is a happy number.

21894151680 is a `hidden beast` number, since 2 + 18 + 9 + 41 + 516 + 80 = 666.

It is a tau number, because it is divible by the number of its divisors (360).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21894151681) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 204618187 + ... + 204618293.

Almost surely, 2^21894151680 is an apocalyptic number.

21894151680 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 21894151680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38731528836).

21894151680 is an abundant number, since it is smaller than the sum of its proper divisors (55568905992).

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

21894151680 is an equidigital number, since it uses as much as digits as its factorization.

21894151680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 326 (or 200 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 45.

The spelling of 21894151680 in words is "twenty-one billion, eight hundred ninety-four million, one hundred fifty-one thousand, six hundred eighty".