21416009 has 4 divisors (see below), whose sum is σ = 22106880. Its totient is φ = 20725140.

The previous prime is 21415991. The next prime is 21416023. The reversal of 21416009 is 90061412.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21416009 - 2⁸ = 21415753 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21416029) 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, 345389 + ... + 345450.

It is an arithmetic number, because the mean of its divisors is an integer number (5526720).

Almost surely, 2^21416009 is an apocalyptic number.

It is an amenable number.

21416009 is a deficient number, since it is larger than the sum of its proper divisors (690871).

21416009 is an equidigital number, since it uses as much as digits as its factorization.

21416009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 690870.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 21416009 is about 4627.7434025667. The cubic root of 21416009 is about 277.7023235710.

The spelling of 21416009 in words is "twenty-one million, four hundred sixteen thousand, nine".