21688542240 has 48 divisors (see below), whose sum is σ = 68318909568. Its totient is φ = 5783611136.

The previous prime is 21688542233. The next prime is 21688542257. The reversal of 21688542240 is 4224588612.

It is a tau number, because it is divible by the number of its divisors (48).

It is a junction number, because it is equal to n+sod(n) for n = 21688542192 and 21688542201.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22591752 + ... + 22592711.

It is an arithmetic number, because the mean of its divisors is an integer number (1423310616).

Almost surely, 2^21688542240 is an apocalyptic number.

21688542240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21688542240 is an abundant number, since it is smaller than the sum of its proper divisors (46630367328).

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

21688542240 is a wasteful number, since it uses less digits than its factorization.

21688542240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45184481 (or 45184473 counting only the distinct ones).

The product of its (nonzero) digits is 245760, while the sum is 42.

The spelling of 21688542240 in words is "twenty-one billion, six hundred eighty-eight million, five hundred forty-two thousand, two hundred forty".