21896409 has 4 divisors (see below), whose sum is σ = 29195216. Its totient is φ = 14597604.

The previous prime is 21896401. The next prime is 21896411. The reversal of 21896409 is 90469812.

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 not a de Polignac number, because 21896409 - 2³ = 21896401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21896401) 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 3 ways as a sum of consecutive naturals, for example, 3649399 + ... + 3649404.

It is an arithmetic number, because the mean of its divisors is an integer number (7298804).

Almost surely, 2^21896409 is an apocalyptic number.

It is an amenable number.

21896409 is a deficient number, since it is larger than the sum of its proper divisors (7298807).

21896409 is an equidigital number, since it uses as much as digits as its factorization.

21896409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7298806.

The product of its (nonzero) digits is 31104, while the sum is 39.

The square root of 21896409 is about 4679.3598921220. The cubic root of 21896409 is about 279.7634439110.

The spelling of 21896409 in words is "twenty-one million, eight hundred ninety-six thousand, four hundred nine".