21209463 has 12 divisors (see below), whose sum is σ = 33421128. Its totient is φ = 12854160.

The previous prime is 21209459. The next prime is 21209467. The reversal of 21209463 is 36490212.

It is an interprime number because it is at equal distance from previous prime (21209459) and next prime (21209467).

It is not a de Polignac number, because 21209463 - 2² = 21209459 is a prime.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21209467) 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 in 11 ways as a sum of consecutive naturals, for example, 107020 + ... + 107217.

It is an arithmetic number, because the mean of its divisors is an integer number (2785094).

Almost surely, 2^21209463 is an apocalyptic number.

21209463 is a deficient number, since it is larger than the sum of its proper divisors (12211665).

21209463 is a wasteful number, since it uses less digits than its factorization.

21209463 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214254 (or 214251 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 21209463 is about 4605.3732747737. The cubic root of 21209463 is about 276.8066743507.

Adding to 21209463 its reverse (36490212), we get a palindrome (57699675).

The spelling of 21209463 in words is "twenty-one million, two hundred nine thousand, four hundred sixty-three".