21897794880 has 896 divisors, whose sum is σ = 90669465600. Its totient is φ = 4926873600.

The previous prime is 21897794879. The next prime is 21897794881. The reversal of 21897794880 is 8849779812.

21897794880 is a `hidden beast` number, since 2 + 1 + 89 + 7 + 79 + 488 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (21897794879) and next prime (21897794881).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21897794881) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 66156315 + ... + 66156645.

It is an arithmetic number, because the mean of its divisors is an integer number (101193600).

Almost surely, 2^21897794880 is an apocalyptic number.

21897794880 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 21897794880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45334732800).

21897794880 is an abundant number, since it is smaller than the sum of its proper divisors (68771670720).

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

21897794880 is a wasteful number, since it uses less digits than its factorization.

21897794880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 420 (or 404 counting only the distinct ones).

The product of its (nonzero) digits is 16257024, while the sum is 63.

The spelling of 21897794880 in words is "twenty-one billion, eight hundred ninety-seven million, seven hundred ninety-four thousand, eight hundred eighty".