21210461 has 2 divisors, whose sum is σ = 21210462. Its totient is φ = 21210460.

The previous prime is 21210433. The next prime is 21210463. The reversal of 21210461 is 16401212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21104836 + 105625 = 4594^2 + 325^2 .

It is a cyclic number.

It is not a de Polignac number, because 21210461 - 2¹⁰ = 21209437 is a prime.

It is a Sophie Germain prime.

Together with 21210463, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21210463) 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, 10605230 + 10605231.

It is an arithmetic number, because the mean of its divisors is an integer number (10605231).

Almost surely, 2^21210461 is an apocalyptic number.

It is an amenable number.

21210461 is a deficient number, since it is larger than the sum of its proper divisors (1).

21210461 is an equidigital number, since it uses as much as digits as its factorization.

21210461 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 21210461 is about 4605.4816251940. The cubic root of 21210461 is about 276.8110159462.

Adding to 21210461 its reverse (16401212), we get a palindrome (37611673).

Subtracting from 21210461 its reverse (16401212), we obtain a square (4809249 = 2193²).

The spelling of 21210461 in words is "twenty-one million, two hundred ten thousand, four hundred sixty-one".