21126404 has 24 divisors (see below), whose sum is σ = 41912640. Its totient is φ = 9237024.

The previous prime is 21126403. The next prime is 21126409. The reversal of 21126404 is 40462112.

It is not an unprimeable number, because it can be changed into a prime (21126403) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9704 + ... + 11679.

It is an arithmetic number, because the mean of its divisors is an integer number (1746360).

Almost surely, 2^21126404 is an apocalyptic number.

It is an amenable number.

21126404 is a deficient number, since it is larger than the sum of its proper divisors (20786236).

21126404 is a wasteful number, since it uses less digits than its factorization.

21126404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21419 (or 21417 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 21126404 is about 4596.3468102396. The cubic root of 21126404 is about 276.4448647296. Note that the first 3 decimals are identical.

Adding to 21126404 its reverse (40462112), we get a palindrome (61588516).

The spelling of 21126404 in words is "twenty-one million, one hundred twenty-six thousand, four hundred four".