21380423 has 2 divisors, whose sum is σ = 21380424. Its totient is φ = 21380422.

The previous prime is 21380399. The next prime is 21380467. The reversal of 21380423 is 32408312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21380423 - 2¹⁰ = 21379399 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21380473) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10690211 + 10690212.

It is an arithmetic number, because the mean of its divisors is an integer number (10690212).

Almost surely, 2^21380423 is an apocalyptic number.

21380423 is a deficient number, since it is larger than the sum of its proper divisors (1).

21380423 is an equidigital number, since it uses as much as digits as its factorization.

21380423 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 21380423 is about 4623.8969495438. The cubic root of 21380423 is about 277.5484232247.

Adding to 21380423 its reverse (32408312), we get a palindrome (53788735).

The spelling of 21380423 in words is "twenty-one million, three hundred eighty thousand, four hundred twenty-three".