21010804 has 6 divisors (see below), whose sum is σ = 36768914. Its totient is φ = 10505400.

The previous prime is 21010763. The next prime is 21010811. The reversal of 21010804 is 40801012.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 12320100 + 8690704 = 3510^2 + 2948^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2626347 + ... + 2626354.

Almost surely, 2^21010804 is an apocalyptic number.

It is an amenable number.

21010804 is a deficient number, since it is larger than the sum of its proper divisors (15758110).

21010804 is a wasteful number, since it uses less digits than its factorization.

21010804 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5252705 (or 5252703 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

The square root of 21010804 is about 4583.7543564201. The cubic root of 21010804 is about 275.9397228866.

Adding to 21010804 its reverse (40801012), we get a palindrome (61811816).

The spelling of 21010804 in words is "twenty-one million, ten thousand, eight hundred four".