21084434728 has 16 divisors (see below), whose sum is σ = 45180931680. Its totient is φ = 9036186288.

The previous prime is 21084434687. The next prime is 21084434737. The reversal of 21084434728 is 82743448012.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 188253826 + ... + 188253937.

It is an arithmetic number, because the mean of its divisors is an integer number (2823808230).

Almost surely, 2^21084434728 is an apocalyptic number.

21084434728 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21084434728 is an abundant number, since it is smaller than the sum of its proper divisors (24096496952).

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

21084434728 is a wasteful number, since it uses less digits than its factorization.

21084434728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 376507776 (or 376507772 counting only the distinct ones).

The product of its (nonzero) digits is 344064, while the sum is 43.

The spelling of 21084434728 in words is "twenty-one billion, eighty-four million, four hundred thirty-four thousand, seven hundred twenty-eight".