21302423 has 4 divisors (see below), whose sum is σ = 21372120. Its totient is φ = 21232728.

The previous prime is 21302419. The next prime is 21302447. The reversal of 21302423 is 32420312.

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 21302423 - 2² = 21302419 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21302483) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34388 + ... + 35001.

It is an arithmetic number, because the mean of its divisors is an integer number (5343030).

Almost surely, 2^21302423 is an apocalyptic number.

21302423 is a deficient number, since it is larger than the sum of its proper divisors (69697).

21302423 is an equidigital number, since it uses as much as digits as its factorization.

21302423 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69696.

The product of its (nonzero) digits is 288, while the sum is 17.

The square root of 21302423 is about 4615.4547988254. The cubic root of 21302423 is about 277.2104948180.

Adding to 21302423 its reverse (32420312), we get a palindrome (53722735).

The spelling of 21302423 in words is "twenty-one million, three hundred two thousand, four hundred twenty-three".