21778884648 has 192 divisors, whose sum is σ = 61626539520. Its totient is φ = 6942412800.

The previous prime is 21778884643. The next prime is 21778884697. The reversal of 21778884648 is 84648887712.

21778884648 is a `hidden beast` number, since 21 + 7 + 78 + 88 + 464 + 8 = 666.

It is not an unprimeable number, because it can be changed into a prime (21778884643) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 70028413 + ... + 70028723.

It is an arithmetic number, because the mean of its divisors is an integer number (320971560).

Almost surely, 2^21778884648 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21778884648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30813269760).

21778884648 is an abundant number, since it is smaller than the sum of its proper divisors (39847654872).

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

21778884648 is a wasteful number, since it uses less digits than its factorization.

21778884648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 728 (or 721 counting only the distinct ones).

The product of its digits is 38535168, while the sum is 63.

The spelling of 21778884648 in words is "twenty-one billion, seven hundred seventy-eight million, eight hundred eighty-four thousand, six hundred forty-eight".