21009683 has 2 divisors, whose sum is σ = 21009684. Its totient is φ = 21009682.

The previous prime is 21009679. The next prime is 21009689. The reversal of 21009683 is 38690012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21009683 - 2² = 21009679 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21009689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10504841 + 10504842.

It is an arithmetic number, because the mean of its divisors is an integer number (10504842).

Almost surely, 2^21009683 is an apocalyptic number.

21009683 is a deficient number, since it is larger than the sum of its proper divisors (1).

21009683 is an equidigital number, since it uses as much as digits as its factorization.

21009683 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 21009683 is about 4583.6320751125. The cubic root of 21009683 is about 275.9348153490.

Adding to 21009683 its reverse (38690012), we get a palindrome (59699695).

The spelling of 21009683 in words is "twenty-one million, nine thousand, six hundred eighty-three".