21828913 has 2 divisors, whose sum is σ = 21828914. Its totient is φ = 21828912.

The previous prime is 21828899. The next prime is 21828931. The reversal of 21828913 is 31982812.

Together with next prime (21828931) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18173169 + 3655744 = 4263^2 + 1912^2 .

It is a cyclic number.

It is not a de Polignac number, because 21828913 - 2⁵ = 21828881 is a prime.

It is a super-3 number, since 3×21828913³ (a number of 23 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (21828973) 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, 10914456 + 10914457.

It is an arithmetic number, because the mean of its divisors is an integer number (10914457).

Almost surely, 2^21828913 is an apocalyptic number.

It is an amenable number.

21828913 is a deficient number, since it is larger than the sum of its proper divisors (1).

21828913 is an equidigital number, since it uses as much as digits as its factorization.

21828913 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6912, while the sum is 34.

The square root of 21828913 is about 4672.1422281433. The cubic root of 21828913 is about 279.4756897410.

The spelling of 21828913 in words is "twenty-one million, eight hundred twenty-eight thousand, nine hundred thirteen".