21430 has 8 divisors (see below), whose sum is σ = 38592. Its totient is φ = 8568.

The previous prime is 21419. The next prime is 21433. The reversal of 21430 is 3412.

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

It is a Harshad number since it is a multiple of its sum of digits (10), and also a Moran number because the ratio is a prime number: 2143 = 21430 / (2 + 1 + 4 + 3 + 0).

It is an Ulam number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21433) 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, 1062 + ... + 1081.

It is an arithmetic number, because the mean of its divisors is an integer number (4824).

2²¹⁴³⁰ is an apocalyptic number.

21430 is a deficient number, since it is larger than the sum of its proper divisors (17162).

21430 is a wasteful number, since it uses less digits than its factorization.

21430 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2150.

The product of its (nonzero) digits is 24, while the sum is 10.

The square root of 21430 is about 146.3898903613. The cubic root of 21430 is about 27.7762784376.

Adding to 21430 its reverse (3412), we get a palindrome (24842).

The spelling of 21430 in words is "twenty-one thousand, four hundred thirty".