21181423 has 2 divisors, whose sum is σ = 21181424. Its totient is φ = 21181422.

The previous prime is 21181411. The next prime is 21181429. The reversal of 21181423 is 32418112.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21181423 - 2¹³ = 21173231 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21181394 and 21181403.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21181429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10590711 + 10590712.

It is an arithmetic number, because the mean of its divisors is an integer number (10590712).

Almost surely, 2^21181423 is an apocalyptic number.

21181423 is a deficient number, since it is larger than the sum of its proper divisors (1).

21181423 is an equidigital number, since it uses as much as digits as its factorization.

21181423 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 384, while the sum is 22.

The square root of 21181423 is about 4602.3279978724. The cubic root of 21181423 is about 276.6846363387.

Adding to 21181423 its reverse (32418112), we get a palindrome (53599535).

The spelling of 21181423 in words is "twenty-one million, one hundred eighty-one thousand, four hundred twenty-three".