21044066840 has 32 divisors (see below), whose sum is σ = 47768179680. Its totient is φ = 8343132672.

The previous prime is 21044066839. The next prime is 21044066909. The reversal of 21044066840 is 4866044012.

It is a self number, because there is not a number n which added to its sum of digits gives 21044066840.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 2323364 + ... + 2332403.

It is an arithmetic number, because the mean of its divisors is an integer number (1492755615).

Almost surely, 2^21044066840 is an apocalyptic number.

21044066840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21044066840 is an abundant number, since it is smaller than the sum of its proper divisors (26724112840).

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

21044066840 is a wasteful number, since it uses less digits than its factorization.

21044066840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4655891 (or 4655887 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 35.

The spelling of 21044066840 in words is "twenty-one billion, forty-four million, sixty-six thousand, eight hundred forty".