21427647 has 8 divisors (see below), whose sum is σ = 28615344. Its totient is φ = 14262528.

The previous prime is 21427643. The next prime is 21427657. The reversal of 21427647 is 74672412.

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

It is not a de Polignac number, because 21427647 - 2² = 21427643 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21427643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3288 + ... + 7325.

It is an arithmetic number, because the mean of its divisors is an integer number (3576918).

Almost surely, 2^21427647 is an apocalyptic number.

21427647 is a deficient number, since it is larger than the sum of its proper divisors (7187697).

21427647 is a wasteful number, since it uses less digits than its factorization.

21427647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11289.

The product of its digits is 18816, while the sum is 33.

The square root of 21427647 is about 4629.0006480881. Note that the first 3 decimals coincide. The cubic root of 21427647 is about 277.7526179464.

The spelling of 21427647 in words is "twenty-one million, four hundred twenty-seven thousand, six hundred forty-seven".