21240654208 has 64 divisors (see below), whose sum is σ = 43813875600. Its totient is φ = 10244892672.

The previous prime is 21240654181. The next prime is 21240654221. The reversal of 21240654208 is 80245604212.

It is a tau number, because it is divible by the number of its divisors (64).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6037666 + ... + 6041182.

Almost surely, 2^21240654208 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 21240654208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21906937800).

21240654208 is an abundant number, since it is smaller than the sum of its proper divisors (22573221392).

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

21240654208 is a wasteful number, since it uses less digits than its factorization.

21240654208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5187 (or 5175 counting only the distinct ones).

The product of its (nonzero) digits is 30720, while the sum is 34.

The spelling of 21240654208 in words is "twenty-one billion, two hundred forty million, six hundred fifty-four thousand, two hundred eight".