21284423 has 2 divisors, whose sum is σ = 21284424. Its totient is φ = 21284422.

The previous prime is 21284411. The next prime is 21284489. The reversal of 21284423 is 32448212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21284423 - 2¹² = 21280327 is a prime.

It is a super-3 number, since 3×21284423³ (a number of 23 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21284392 and 21284401.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21284723) 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 as a sum of consecutive naturals, namely, 10642211 + 10642212.

It is an arithmetic number, because the mean of its divisors is an integer number (10642212).

Almost surely, 2^21284423 is an apocalyptic number.

21284423 is a deficient number, since it is larger than the sum of its proper divisors (1).

21284423 is an equidigital number, since it uses as much as digits as its factorization.

21284423 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3072, while the sum is 26.

The square root of 21284423 is about 4613.5044163846. The cubic root of 21284423 is about 277.1323942348.

The spelling of 21284423 in words is "twenty-one million, two hundred eighty-four thousand, four hundred twenty-three".