21406489609 has 2 divisors, whose sum is σ = 21406489610. Its totient is φ = 21406489608.

The previous prime is 21406489583. The next prime is 21406489639. The reversal of 21406489609 is 90698460412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12895873600 + 8510616009 = 113560^2 + 92253^2 .

It is a cyclic number.

It is not a de Polignac number, because 21406489609 - 2¹³ = 21406481417 is a prime.

It is not a weakly prime, because it can be changed into another prime (21406489639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10703244804 + 10703244805.

It is an arithmetic number, because the mean of its divisors is an integer number (10703244805).

Almost surely, 2^21406489609 is an apocalyptic number.

It is an amenable number.

21406489609 is a deficient number, since it is larger than the sum of its proper divisors (1).

21406489609 is an equidigital number, since it uses as much as digits as its factorization.

21406489609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 746496, while the sum is 49.

The spelling of 21406489609 in words is "twenty-one billion, four hundred six million, four hundred eighty-nine thousand, six hundred nine".