21430307 has 4 divisors (see below), whose sum is σ = 21651336. Its totient is φ = 21209280.

The previous prime is 21430301. The next prime is 21430327. The reversal of 21430307 is 70303412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21430307 - 2⁴ = 21430291 is a prime.

It is a super-3 number, since 3×21430307³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

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

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21430301) 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, 110369 + ... + 110562.

It is an arithmetic number, because the mean of its divisors is an integer number (5412834).

Almost surely, 2^21430307 is an apocalyptic number.

21430307 is a deficient number, since it is larger than the sum of its proper divisors (221029).

21430307 is an equidigital number, since it uses as much as digits as its factorization.

21430307 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221028.

The product of its (nonzero) digits is 504, while the sum is 20.

The square root of 21430307 is about 4629.2879582070. The cubic root of 21430307 is about 277.7641107528.

Adding to 21430307 its reverse (70303412), we get a palindrome (91733719).

The spelling of 21430307 in words is "twenty-one million, four hundred thirty thousand, three hundred seven".