21547508668 has 12 divisors (see below), whose sum is σ = 43095017392. Its totient is φ = 9234646560.

The previous prime is 21547508659. The next prime is 21547508693. The reversal of 21547508668 is 86680574512.

It is a happy number.

21547508668 is an admirable number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 384776913 + ... + 384776968.

Almost surely, 2^21547508668 is an apocalyptic number.

21547508668 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21547508668 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21547508668 is a wasteful number, since it uses less digits than its factorization.

21547508668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 769553892 (or 769553890 counting only the distinct ones).

The product of its (nonzero) digits is 3225600, while the sum is 52.

The spelling of 21547508668 in words is "twenty-one billion, five hundred forty-seven million, five hundred eight thousand, six hundred sixty-eight".