21419809 has 4 divisors (see below), whose sum is σ = 21429504. Its totient is φ = 21410116.

The previous prime is 21419807. The next prime is 21419837. The reversal of 21419809 is 90891412.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21419809 - 2¹ = 21419807 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21419807) 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, 264 + ... + 6550.

It is an arithmetic number, because the mean of its divisors is an integer number (5357376).

Almost surely, 2^21419809 is an apocalyptic number.

It is an amenable number.

21419809 is a deficient number, since it is larger than the sum of its proper divisors (9695).

21419809 is an equidigital number, since it uses as much as digits as its factorization.

21419809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9694.

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 21419809 is about 4628.1539516313. The cubic root of 21419809 is about 277.7187475216.

The spelling of 21419809 in words is "twenty-one million, four hundred nineteen thousand, eight hundred nine".