21505509484 has 12 divisors (see below), whose sum is σ = 37636434864. Its totient is φ = 10752242384.

The previous prime is 21505509433. The next prime is 21505509517. The reversal of 21505509484 is 48490550512.

It is a self number, because there is not a number n which added to its sum of digits gives 21505509484.

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, 24307 + ... + 208810.

It is an arithmetic number, because the mean of its divisors is an integer number (3136369572).

Almost surely, 2^21505509484 is an apocalyptic number.

It is an amenable number.

21505509484 is a deficient number, since it is larger than the sum of its proper divisors (16130925380).

21505509484 is a wasteful number, since it uses less digits than its factorization.

21505509484 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 256184 (or 256182 counting only the distinct ones).

The product of its (nonzero) digits is 288000, while the sum is 43.

The spelling of 21505509484 in words is "twenty-one billion, five hundred five million, five hundred nine thousand, four hundred eighty-four".