21549247 has 8 divisors (see below), whose sum is σ = 22300160. Its totient is φ = 20801880.

The previous prime is 21549221. The next prime is 21549257. The reversal of 21549247 is 74294512.

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 21549247 - 2⁷ = 21549119 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21549257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18628 + ... + 19750.

It is an arithmetic number, because the mean of its divisors is an integer number (2787520).

Almost surely, 2^21549247 is an apocalyptic number.

21549247 is a deficient number, since it is larger than the sum of its proper divisors (750913).

21549247 is a wasteful number, since it uses less digits than its factorization.

21549247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1773.

The product of its digits is 20160, while the sum is 34.

The square root of 21549247 is about 4642.1166508394. The cubic root of 21549247 is about 278.2770343619.

The spelling of 21549247 in words is "twenty-one million, five hundred forty-nine thousand, two hundred forty-seven".