21230421 has 4 divisors (see below), whose sum is σ = 28307232. Its totient is φ = 14153612.

The previous prime is 21230401. The next prime is 21230431. The reversal of 21230421 is 12403212.

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 21230421 - 2⁵ = 21230389 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21230421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21230401) 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, 3538401 + ... + 3538406.

It is an arithmetic number, because the mean of its divisors is an integer number (7076808).

Almost surely, 2^21230421 is an apocalyptic number.

It is an amenable number.

21230421 is a deficient number, since it is larger than the sum of its proper divisors (7076811).

21230421 is an equidigital number, since it uses as much as digits as its factorization.

21230421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7076810.

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 21230421 is about 4607.6480985422. The cubic root of 21230421 is about 276.8978192716.

Adding to 21230421 its reverse (12403212), we get a palindrome (33633633).

The spelling of 21230421 in words is "twenty-one million, two hundred thirty thousand, four hundred twenty-one".