21123436 has 12 divisors (see below), whose sum is σ = 36999928. Its totient is φ = 10552032.

The previous prime is 21123391. The next prime is 21123457. The reversal of 21123436 is 63432112.

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, 5035 + ... + 8221.

Almost surely, 2^21123436 is an apocalyptic number.

It is an amenable number.

21123436 is a deficient number, since it is larger than the sum of its proper divisors (15876492).

21123436 is a wasteful number, since it uses less digits than its factorization.

21123436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4848 (or 4846 counting only the distinct ones).

The product of its digits is 864, while the sum is 22.

The square root of 21123436 is about 4596.0239337932. The cubic root of 21123436 is about 276.4319184218.

Adding to 21123436 its reverse (63432112), we get a palindrome (84555548).

The spelling of 21123436 in words is "twenty-one million, one hundred twenty-three thousand, four hundred thirty-six".