21208474 has 24 divisors (see below), whose sum is σ = 38013300. Its totient is φ = 8842176.

The previous prime is 21208441. The next prime is 21208487. The reversal of 21208474 is 47480212.

It can be written as a sum of positive squares in 2 ways, for example, as 20766249 + 442225 = 4557^2 + 665^2 .

It is a congruent number.

It is an unprimeable number.

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, 702 + ... + 6550.

Almost surely, 2^21208474 is an apocalyptic number.

21208474 is a deficient number, since it is larger than the sum of its proper divisors (16804826).

21208474 is a wasteful number, since it uses less digits than its factorization.

21208474 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5902 (or 5895 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 28.

The square root of 21208474 is about 4605.2658989466. The cubic root of 21208474 is about 276.8023717735.

Adding to 21208474 its reverse (47480212), we get a palindrome (68688686).

The spelling of 21208474 in words is "twenty-one million, two hundred eight thousand, four hundred seventy-four".