21042236 has 6 divisors (see below), whose sum is σ = 36823920. Its totient is φ = 10521116.

The previous prime is 21042223. The next prime is 21042251. The reversal of 21042236 is 63224012.

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, 2630276 + ... + 2630283.

It is an arithmetic number, because the mean of its divisors is an integer number (6137320).

Almost surely, 2^21042236 is an apocalyptic number.

It is an amenable number.

21042236 is a deficient number, since it is larger than the sum of its proper divisors (15781684).

21042236 is a wasteful number, since it uses less digits than its factorization.

21042236 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5260563 (or 5260561 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 20.

The square root of 21042236 is about 4587.1817055791. The cubic root of 21042236 is about 276.0772555559.

Adding to 21042236 its reverse (63224012), we get a palindrome (84266248).

The spelling of 21042236 in words is "twenty-one million, forty-two thousand, two hundred thirty-six".