21209963 has 2 divisors, whose sum is σ = 21209964. Its totient is φ = 21209962.

The previous prime is 21209957. The next prime is 21210011. The reversal of 21209963 is 36990212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21209963 - 2¹⁰ = 21208939 is a prime.

It is a super-2 number, since 2×21209963² = 899725060922738, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21209563) 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, 10604981 + 10604982.

It is an arithmetic number, because the mean of its divisors is an integer number (10604982).

Almost surely, 2^21209963 is an apocalyptic number.

21209963 is a deficient number, since it is larger than the sum of its proper divisors (1).

21209963 is an equidigital number, since it uses as much as digits as its factorization.

21209963 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5832, while the sum is 32.

The square root of 21209963 is about 4605.4275588701. The cubic root of 21209963 is about 276.8088495158.

The spelling of 21209963 in words is "twenty-one million, two hundred nine thousand, nine hundred sixty-three".