21267009 has 8 divisors (see below), whose sum is σ = 31506720. Its totient is φ = 14177988.

The previous prime is 21266977. The next prime is 21267011. The reversal of 21267009 is 90076212.

It is not a de Polignac number, because 21267009 - 2⁵ = 21266977 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 787667 = 21267009 / (2 + 1 + 2 + 6 + 7 + 0 + 0 + 9).

It is not an unprimeable number, because it can be changed into a prime (21267049) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 393807 + ... + 393860.

It is an arithmetic number, because the mean of its divisors is an integer number (3938340).

Almost surely, 2^21267009 is an apocalyptic number.

It is an amenable number.

21267009 is a deficient number, since it is larger than the sum of its proper divisors (10239711).

21267009 is an equidigital number, since it uses as much as digits as its factorization.

21267009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 787676 (or 787670 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 21267009 is about 4611.6167447003. The cubic root of 21267009 is about 277.0567943426.

The spelling of 21267009 in words is "twenty-one million, two hundred sixty-seven thousand, nine".