21685472 has 24 divisors (see below), whose sum is σ = 45205776. Its totient is φ = 10204672.

The previous prime is 21685457. The next prime is 21685483. The reversal of 21685472 is 27458612.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19388 + ... + 20475.

It is an arithmetic number, because the mean of its divisors is an integer number (1883574).

Almost surely, 2^21685472 is an apocalyptic number.

It is an amenable number.

21685472 is an abundant number, since it is smaller than the sum of its proper divisors (23520304).

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

21685472 is a wasteful number, since it uses less digits than its factorization.

21685472 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39890 (or 39882 counting only the distinct ones).

The product of its digits is 26880, while the sum is 35.

The square root of 21685472 is about 4656.7662599705. The cubic root of 21685472 is about 278.8621853332.

The spelling of 21685472 in words is "twenty-one million, six hundred eighty-five thousand, four hundred seventy-two".