21547721484 has 18 divisors (see below), whose sum is σ = 54467851620. Its totient is φ = 7182573816.

The previous prime is 21547721471. The next prime is 21547721497. The reversal of 21547721484 is 48412774512.

21547721484 is a `hidden beast` number, since 2 + 1 + 547 + 7 + 21 + 4 + 84 = 666.

It is an interprime number because it is at equal distance from previous prime (21547721471) and next prime (21547721497).

It is a tau number, because it is divible by the number of its divisors (18).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 299273874 + ... + 299273945.

Almost surely, 2^21547721484 is an apocalyptic number.

It is an amenable number.

21547721484 is an abundant number, since it is smaller than the sum of its proper divisors (32920130136).

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

21547721484 is a wasteful number, since it uses less digits than its factorization.

21547721484 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 598547829 (or 598547824 counting only the distinct ones).

The product of its digits is 501760, while the sum is 45.

The spelling of 21547721484 in words is "twenty-one billion, five hundred forty-seven million, seven hundred twenty-one thousand, four hundred eighty-four".