21053009 has 2 divisors, whose sum is σ = 21053010. Its totient is φ = 21053008.

The previous prime is 21052979. The next prime is 21053017. The reversal of 21053009 is 90035012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11424400 + 9628609 = 3380^2 + 3103^2 .

It is a cyclic number.

It is not a de Polignac number, because 21053009 - 2¹² = 21048913 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21053059) 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, 10526504 + 10526505.

It is an arithmetic number, because the mean of its divisors is an integer number (10526505).

Almost surely, 2^21053009 is an apocalyptic number.

It is an amenable number.

21053009 is a deficient number, since it is larger than the sum of its proper divisors (1).

21053009 is an equidigital number, since it uses as much as digits as its factorization.

21053009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 270, while the sum is 20.

The square root of 21053009 is about 4588.3558057326. The cubic root of 21053009 is about 276.1243619701.

The spelling of 21053009 in words is "twenty-one million, fifty-three thousand, nine".