21305101 has 2 divisors, whose sum is σ = 21305102. Its totient is φ = 21305100.

The previous prime is 21305071. The next prime is 21305113. The reversal of 21305101 is 10150312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13176900 + 8128201 = 3630^2 + 2851^2 .

It is a cyclic number.

It is not a de Polignac number, because 21305101 - 2⁷ = 21304973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21305191) 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, 10652550 + 10652551.

It is an arithmetic number, because the mean of its divisors is an integer number (10652551).

Almost surely, 2^21305101 is an apocalyptic number.

It is an amenable number.

21305101 is a deficient number, since it is larger than the sum of its proper divisors (1).

21305101 is an equidigital number, since it uses as much as digits as its factorization.

21305101 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 30, while the sum is 13.

The square root of 21305101 is about 4615.7449019633. The cubic root of 21305101 is about 277.2221106891. Note that the first 3 decimals are identical.

Adding to 21305101 its reverse (10150312), we get a palindrome (31455413).

The spelling of 21305101 in words is "twenty-one million, three hundred five thousand, one hundred one".