21430421 has 8 divisors (see below), whose sum is σ = 22866624. Its totient is φ = 20013760.

The previous prime is 21430403. The next prime is 21430433. The reversal of 21430421 is 12403412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21430421 - 2¹⁴ = 21414037 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21430421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21430481) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2585 + ... + 7038.

It is an arithmetic number, because the mean of its divisors is an integer number (2858328).

Almost surely, 2^21430421 is an apocalyptic number.

It is an amenable number.

21430421 is a deficient number, since it is larger than the sum of its proper divisors (1436203).

21430421 is a wasteful number, since it uses less digits than its factorization.

21430421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9771.

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 21430421 is about 4629.3002710993. The cubic root of 21430421 is about 277.7646032804.

Adding to 21430421 its reverse (12403412), we get a palindrome (33833833).

The spelling of 21430421 in words is "twenty-one million, four hundred thirty thousand, four hundred twenty-one".