21895856640 has 480 divisors, whose sum is σ = 87428689920. Its totient is φ = 4960714752.

The previous prime is 21895856617. The next prime is 21895856701. The reversal of 21895856640 is 4665859812.

21895856640 is a `hidden beast` number, since 2 + 18 + 9 + 585 + 6 + 6 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (480).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 20482026 + ... + 20483094.

It is an arithmetic number, because the mean of its divisors is an integer number (182143104).

Almost surely, 2^21895856640 is an apocalyptic number.

21895856640 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 21895856640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43714344960).

21895856640 is an abundant number, since it is smaller than the sum of its proper divisors (65532833280).

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

21895856640 is a wasteful number, since it uses less digits than its factorization.

21895856640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1232 (or 1213 counting only the distinct ones).

The product of its (nonzero) digits is 4147200, while the sum is 54.

The spelling of 21895856640 in words is "twenty-one billion, eight hundred ninety-five million, eight hundred fifty-six thousand, six hundred forty".