21212603 has 2 divisors, whose sum is σ = 21212604. Its totient is φ = 21212602.

The previous prime is 21212593. The next prime is 21212623. The reversal of 21212603 is 30621212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21212603 - 2²² = 17018299 is a prime.

It is not a weakly prime, because it can be changed into another prime (21212623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606301 + 10606302.

It is an arithmetic number, because the mean of its divisors is an integer number (10606302).

Almost surely, 2^21212603 is an apocalyptic number.

21212603 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212603 is an equidigital number, since it uses as much as digits as its factorization.

21212603 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 21212603 is about 4605.7141682914. The cubic root of 21212603 is about 276.8203338206.

Adding to 21212603 its reverse (30621212), we get a palindrome (51833815).

The spelling of 21212603 in words is "twenty-one million, two hundred twelve thousand, six hundred three".