21014009 has 4 divisors (see below), whose sum is σ = 21738660. Its totient is φ = 20289360.

The previous prime is 21013997. The next prime is 21014041. The reversal of 21014009 is 90041012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14227984 + 6786025 = 3772^2 + 2605^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21014009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21014069) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 362282 + ... + 362339.

It is an arithmetic number, because the mean of its divisors is an integer number (5434665).

Almost surely, 2^21014009 is an apocalyptic number.

21014009 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21014009 is a deficient number, since it is larger than the sum of its proper divisors (724651).

21014009 is an equidigital number, since it uses as much as digits as its factorization.

21014009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 724650.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 21014009 is about 4584.1039473380. The cubic root of 21014009 is about 275.9537528407.

The spelling of 21014009 in words is "twenty-one million, fourteen thousand, nine".