21047680 has 32 divisors (see below), whose sum is σ = 50318640. Its totient is φ = 8418816.

The previous prime is 21047671. The next prime is 21047713. The reversal of 21047680 is 8674012.

It is a tau number, because it is divible by the number of its divisors (32).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15804 + ... + 17083.

Almost surely, 2^21047680 is an apocalyptic number.

21047680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21047680 is an abundant number, since it is smaller than the sum of its proper divisors (29270960).

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

21047680 is an equidigital number, since it uses as much as digits as its factorization.

21047680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32906 (or 32894 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 21047680 is about 4587.7750598738. The cubic root of 21047680 is about 276.1010621987.

The spelling of 21047680 in words is "twenty-one million, forty-seven thousand, six hundred eighty".