21104647 has 2 divisors, whose sum is σ = 21104648. Its totient is φ = 21104646.

The previous prime is 21104641. The next prime is 21104669. The reversal of 21104647 is 74640112.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21104647 is a prime.

It is a super-2 number, since 2×21104647² = 890812249989218, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21104641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10552323 + 10552324.

It is an arithmetic number, because the mean of its divisors is an integer number (10552324).

Almost surely, 2^21104647 is an apocalyptic number.

21104647 is a deficient number, since it is larger than the sum of its proper divisors (1).

21104647 is an equidigital number, since it uses as much as digits as its factorization.

21104647 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 21104647 is about 4593.9794296448. The cubic root of 21104647 is about 276.3499333376.

Adding to 21104647 its reverse (74640112), we get a palindrome (95744759).

The spelling of 21104647 in words is "twenty-one million, one hundred four thousand, six hundred forty-seven".