21430305 has 32 divisors (see below), whose sum is σ = 41032320. Its totient is φ = 10549440.

The previous prime is 21430301. The next prime is 21430327. The reversal of 21430305 is 50303412.

It is not a de Polignac number, because 21430305 - 2² = 21430301 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (21430301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4351 + ... + 7860.

It is an arithmetic number, because the mean of its divisors is an integer number (1282260).

Almost surely, 2^21430305 is an apocalyptic number.

It is an amenable number.

21430305 is a deficient number, since it is larger than the sum of its proper divisors (19602015).

21430305 is a wasteful number, since it uses less digits than its factorization.

21430305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12238 (or 12232 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 18.

The square root of 21430305 is about 4629.2877421910. The cubic root of 21430305 is about 277.7641021119.

Adding to 21430305 its reverse (50303412), we get a palindrome (71733717).

The spelling of 21430305 in words is "twenty-one million, four hundred thirty thousand, three hundred five".