21248647 has 8 divisors (see below), whose sum is σ = 24315552. Its totient is φ = 18189600.

The previous prime is 21248641. The next prime is 21248651. The reversal of 21248647 is 74684212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21248647 - 2³ = 21248639 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21248641) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 5997 + ... + 8857.

It is an arithmetic number, because the mean of its divisors is an integer number (3039444).

Almost surely, 2^21248647 is an apocalyptic number.

21248647 is a deficient number, since it is larger than the sum of its proper divisors (3066905).

21248647 is a wasteful number, since it uses less digits than its factorization.

21248647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3929.

The product of its digits is 21504, while the sum is 34.

The square root of 21248647 is about 4609.6254728557. The cubic root of 21248647 is about 276.9770341580.

The spelling of 21248647 in words is "twenty-one million, two hundred forty-eight thousand, six hundred forty-seven".