21251204 has 12 divisors (see below), whose sum is σ = 40050444. Its totient is φ = 9808224.

The previous prime is 21251201. The next prime is 21251239. The reversal of 21251204 is 40215212.

It can be written as a sum of positive squares in 2 ways, for example, as 4194304 + 17056900 = 2048^2 + 4130^2 .

It is a super-2 number, since 2×21251204² = 903227342899232, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21251201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 204287 + ... + 204390.

It is an arithmetic number, because the mean of its divisors is an integer number (3337537).

Almost surely, 2^21251204 is an apocalyptic number.

It is an amenable number.

21251204 is a deficient number, since it is larger than the sum of its proper divisors (18799240).

21251204 is a wasteful number, since it uses less digits than its factorization.

21251204 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 408694 (or 408692 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21251204 is about 4609.9028189323. The cubic root of 21251204 is about 276.9881439143.

Adding to 21251204 its reverse (40215212), we get a palindrome (61466416).

The spelling of 21251204 in words is "twenty-one million, two hundred fifty-one thousand, two hundred four".