21813079680 has 448 divisors, whose sum is σ = 89367177600. Its totient is φ = 4985100288.

The previous prime is 21813079663. The next prime is 21813079681. The reversal of 21813079680 is 8697031812.

21813079680 is a `hidden beast` number, since 2 + 181 + 307 + 96 + 80 = 666.

It is a tau number, because it is divible by the number of its divisors (448).

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

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

It is not an unprimeable number, because it can be changed into a prime (21813079681) by changing a digit.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 3262581 + ... + 3269259.

Almost surely, 2^21813079680 is an apocalyptic number.

21813079680 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 21813079680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44683588800).

21813079680 is an abundant number, since it is smaller than the sum of its proper divisors (67554097920).

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

21813079680 is an frugal number, since it uses more digits than its factorization.

21813079680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6723 (or 6696 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 45.

The spelling of 21813079680 in words is "twenty-one billion, eight hundred thirteen million, seventy-nine thousand, six hundred eighty".