21221404 has 24 divisors (see below), whose sum is σ = 39266640. Its totient is φ = 10007424.

The previous prime is 21221383. The next prime is 21221411. The reversal of 21221404 is 40412212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21792 + ... + 22744.

It is an arithmetic number, because the mean of its divisors is an integer number (1636110).

Almost surely, 2^21221404 is an apocalyptic number.

It is an amenable number.

21221404 is a deficient number, since it is larger than the sum of its proper divisors (18045236).

21221404 is a wasteful number, since it uses less digits than its factorization.

21221404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1269 (or 1267 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 16.

The square root of 21221404 is about 4606.6695127825. The cubic root of 21221404 is about 276.8586123054.

Adding to 21221404 its reverse (40412212), we get a palindrome (61633616).

The spelling of 21221404 in words is "twenty-one million, two hundred twenty-one thousand, four hundred four".