21270009 has 16 divisors (see below), whose sum is σ = 31335552. Its totient is φ = 12764928.

The previous prime is 21269981. The next prime is 21270017. The reversal of 21270009 is 90007212.

It is a happy number.

It is not a de Polignac number, because 21270009 - 2¹² = 21265913 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21270089) 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 in 15 ways as a sum of consecutive naturals, for example, 7894 + ... + 10239.

It is an arithmetic number, because the mean of its divisors is an integer number (1958472).

Almost surely, 2^21270009 is an apocalyptic number.

It is an amenable number.

21270009 is a deficient number, since it is larger than the sum of its proper divisors (10065543).

21270009 is a wasteful number, since it uses less digits than its factorization.

21270009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18176.

The product of its (nonzero) digits is 252, while the sum is 21.

The square root of 21270009 is about 4611.9419987680. The cubic root of 21270009 is about 277.0698212693.

The spelling of 21270009 in words is "twenty-one million, two hundred seventy thousand, nine".