21364009 has 2 divisors, whose sum is σ = 21364010. Its totient is φ = 21364008.

The previous prime is 21364001. The next prime is 21364061. The reversal of 21364009 is 90046312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21187609 + 176400 = 4603^2 + 420^2 .

It is a cyclic number.

It is not a de Polignac number, because 21364009 - 2³ = 21364001 is a prime.

It is not a weakly prime, because it can be changed into another prime (21364001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10682004 + 10682005.

It is an arithmetic number, because the mean of its divisors is an integer number (10682005).

Almost surely, 2^21364009 is an apocalyptic number.

It is an amenable number.

21364009 is a deficient number, since it is larger than the sum of its proper divisors (1).

21364009 is an equidigital number, since it uses as much as digits as its factorization.

21364009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 21364009 is about 4622.1216989603. The cubic root of 21364009 is about 277.4773793211.

The spelling of 21364009 in words is "twenty-one million, three hundred sixty-four thousand, nine".