21284723 has 2 divisors, whose sum is σ = 21284724. Its totient is φ = 21284722.

The previous prime is 21284707. The next prime is 21284741. The reversal of 21284723 is 32748212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21284723 - 2⁴ = 21284707 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21284743) 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, 10642361 + 10642362.

It is an arithmetic number, because the mean of its divisors is an integer number (10642362).

Almost surely, 2^21284723 is an apocalyptic number.

21284723 is a deficient number, since it is larger than the sum of its proper divisors (1).

21284723 is an equidigital number, since it uses as much as digits as its factorization.

21284723 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5376, while the sum is 29.

The square root of 21284723 is about 4613.5369295151. The cubic root of 21284723 is about 277.1336962719.

The spelling of 21284723 in words is "twenty-one million, two hundred eighty-four thousand, seven hundred twenty-three".