21210404 has 12 divisors (see below), whose sum is σ = 37486428. Its totient is φ = 10500000.

The previous prime is 21210389. The next prime is 21210433. The reversal of 21210404 is 40401212.

It can be written as a sum of positive squares in 2 ways, for example, as 14440000 + 6770404 = 3800^2 + 2602^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25847 + ... + 26654.

It is an arithmetic number, because the mean of its divisors is an integer number (3123869).

Almost surely, 2^21210404 is an apocalyptic number.

It is an amenable number.

21210404 is a deficient number, since it is larger than the sum of its proper divisors (16276024).

21210404 is a wasteful number, since it uses less digits than its factorization.

21210404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52606 (or 52604 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 21210404 is about 4605.4754369120. The cubic root of 21210404 is about 276.8107679830.

Adding to 21210404 its reverse (40401212), we get a palindrome (61611616).

The spelling of 21210404 in words is "twenty-one million, two hundred ten thousand, four hundred four".