21030923 has 2 divisors, whose sum is σ = 21030924. Its totient is φ = 21030922.

The previous prime is 21030899. The next prime is 21030931. The reversal of 21030923 is 32903012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21030923 - 2¹⁸ = 20768779 is a prime.

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

It is a junction number, because it is equal to n+sod(n) for n = 21030895 and 21030904.

It is not a weakly prime, because it can be changed into another prime (21030943) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10515461 + 10515462.

It is an arithmetic number, because the mean of its divisors is an integer number (10515462).

Almost surely, 2^21030923 is an apocalyptic number.

21030923 is a deficient number, since it is larger than the sum of its proper divisors (1).

21030923 is an equidigital number, since it uses as much as digits as its factorization.

21030923 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 20.

The square root of 21030923 is about 4585.9484297144. The cubic root of 21030923 is about 276.0277706076.

Adding to 21030923 its reverse (32903012), we get a palindrome (53933935).

The spelling of 21030923 in words is "twenty-one million, thirty thousand, nine hundred twenty-three".