21417409 has 8 divisors (see below), whose sum is σ = 23221800. Its totient is φ = 19635456.

The previous prime is 21417377. The next prime is 21417437. The reversal of 21417409 is 90471412.

It can be written as a sum of positive squares in 4 ways, for example, as 760384 + 20657025 = 872^2 + 4545^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21417409 - 2⁵ = 21417377 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21417449) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3592 + ... + 7465.

It is an arithmetic number, because the mean of its divisors is an integer number (2902725).

Almost surely, 2^21417409 is an apocalyptic number.

It is an amenable number.

21417409 is a deficient number, since it is larger than the sum of its proper divisors (1804391).

21417409 is a wasteful number, since it uses less digits than its factorization.

21417409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11219.

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 21417409 is about 4627.8946617225. The cubic root of 21417409 is about 277.7083747262.

The spelling of 21417409 in words is "twenty-one million, four hundred seventeen thousand, four hundred nine".