21704928 has 48 divisors (see below), whose sum is σ = 65116800. Its totient is φ = 6201216.

The previous prime is 21704887. The next prime is 21704933. The reversal of 21704928 is 82940712.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (48).

It is a super-2 number, since 2×21704928² = 942207798970368, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15478 + ... + 16821.

It is an arithmetic number, because the mean of its divisors is an integer number (1356600).

Almost surely, 2^21704928 is an apocalyptic number.

21704928 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21704928 is an abundant number, since it is smaller than the sum of its proper divisors (43411872).

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

21704928 is a wasteful number, since it uses less digits than its factorization.

21704928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32319 (or 32311 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 33.

The square root of 21704928 is about 4658.8547949040. The cubic root of 21704928 is about 278.9455579080.

The spelling of 21704928 in words is "twenty-one million, seven hundred four thousand, nine hundred twenty-eight".