21494609 has 4 divisors (see below), whose sum is σ = 21541104. Its totient is φ = 21448116.

The previous prime is 21494573. The next prime is 21494617. The reversal of 21494609 is 90649412.

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 21494609 - 2⁸ = 21494353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21494639) 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, 22547 + ... + 23480.

It is an arithmetic number, because the mean of its divisors is an integer number (5385276).

Almost surely, 2^21494609 is an apocalyptic number.

It is an amenable number.

21494609 is a deficient number, since it is larger than the sum of its proper divisors (46495).

21494609 is an equidigital number, since it uses as much as digits as its factorization.

21494609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46494.

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 21494609 is about 4636.2278848219. The cubic root of 21494609 is about 278.0416453319.

The spelling of 21494609 in words is "twenty-one million, four hundred ninety-four thousand, six hundred nine".