21430023 has 4 divisors (see below), whose sum is σ = 28573368. Its totient is φ = 14286680.

The previous prime is 21430007. The next prime is 21430033. The reversal of 21430023 is 32003412.

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 21430023 - 2⁴ = 21430007 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21429984 and 21430011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21430033) 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, 3571668 + ... + 3571673.

It is an arithmetic number, because the mean of its divisors is an integer number (7143342).

Almost surely, 2^21430023 is an apocalyptic number.

21430023 is a deficient number, since it is larger than the sum of its proper divisors (7143345).

21430023 is an equidigital number, since it uses as much as digits as its factorization.

21430023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7143344.

The product of its (nonzero) digits is 144, while the sum is 15.

The square root of 21430023 is about 4629.2572838415. The cubic root of 21430023 is about 277.7628837466.

Adding to 21430023 its reverse (32003412), we get a palindrome (53433435).

The spelling of 21430023 in words is "twenty-one million, four hundred thirty thousand, twenty-three".