21339647 has 6 divisors (see below), whose sum is σ = 24823728. Its totient is φ = 18291084.

The previous prime is 21339629. The next prime is 21339649. The reversal of 21339647 is 74693312.

It is not a de Polignac number, because 21339647 - 2⁸ = 21339391 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21339649) 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 5 ways as a sum of consecutive naturals, for example, 217703 + ... + 217800.

It is an arithmetic number, because the mean of its divisors is an integer number (4137288).

Almost surely, 2^21339647 is an apocalyptic number.

21339647 is a deficient number, since it is larger than the sum of its proper divisors (3484081).

21339647 is an equidigital number, since it uses as much as digits as its factorization.

21339647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 435517 (or 435510 counting only the distinct ones).

The product of its digits is 27216, while the sum is 35.

The square root of 21339647 is about 4619.4855774209. The cubic root of 21339647 is about 277.3718673664.

The spelling of 21339647 in words is "twenty-one million, three hundred thirty-nine thousand, six hundred forty-seven".