21147856 has 20 divisors (see below), whose sum is σ = 42756192. Its totient is φ = 10114016.

The previous prime is 21147851. The next prime is 21147869. The reversal of 21147856 is 65874112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21147851) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28366 + ... + 29101.

Almost surely, 2^21147856 is an apocalyptic number.

It is an amenable number.

21147856 is an abundant number, since it is smaller than the sum of its proper divisors (21608336).

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

21147856 is a wasteful number, since it uses less digits than its factorization.

21147856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57498 (or 57492 counting only the distinct ones).

The product of its digits is 13440, while the sum is 34.

The square root of 21147856 is about 4598.6798105543. The cubic root of 21147856 is about 276.5384015369.

The spelling of 21147856 in words is "twenty-one million, one hundred forty-seven thousand, eight hundred fifty-six".