21752009 has 2 divisors, whose sum is σ = 21752010. Its totient is φ = 21752008.

The previous prime is 21751999. The next prime is 21752021. The reversal of 21752009 is 90025712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18318400 + 3433609 = 4280^2 + 1853^2 .

It is a cyclic number.

It is not a de Polignac number, because 21752009 - 2⁸ = 21751753 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21752039) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10876004 + 10876005.

It is an arithmetic number, because the mean of its divisors is an integer number (10876005).

Almost surely, 2^21752009 is an apocalyptic number.

It is an amenable number.

21752009 is a deficient number, since it is larger than the sum of its proper divisors (1).

21752009 is an equidigital number, since it uses as much as digits as its factorization.

21752009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1260, while the sum is 26.

The square root of 21752009 is about 4663.9049089792. The cubic root of 21752009 is about 279.1471027898.

The spelling of 21752009 in words is "twenty-one million, seven hundred fifty-two thousand, nine".