21710609 has 2 divisors, whose sum is σ = 21710610. Its totient is φ = 21710608.

The previous prime is 21710603. The next prime is 21710617. The reversal of 21710609 is 90601712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13300609 + 8410000 = 3647^2 + 2900^2 .

It is a cyclic number.

It is not a de Polignac number, because 21710609 - 2¹⁶ = 21645073 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is equal to p_1372076 and since 21710609 and 1372076 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21710603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10855304 + 10855305.

It is an arithmetic number, because the mean of its divisors is an integer number (10855305).

Almost surely, 2^21710609 is an apocalyptic number.

It is an amenable number.

21710609 is a deficient number, since it is larger than the sum of its proper divisors (1).

21710609 is an equidigital number, since it uses as much as digits as its factorization.

21710609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 756, while the sum is 26.

The square root of 21710609 is about 4659.4644542050. The cubic root of 21710609 is about 278.9698926501.

The spelling of 21710609 in words is "twenty-one million, seven hundred ten thousand, six hundred nine".