21043436 has 12 divisors (see below), whose sum is σ = 38427312. Its totient is φ = 10064208.

The previous prime is 21043423. The next prime is 21043441. The reversal of 21043436 is 63434012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (23).

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, 114275 + ... + 114458.

It is an arithmetic number, because the mean of its divisors is an integer number (3202276).

Almost surely, 2^21043436 is an apocalyptic number.

It is an amenable number.

21043436 is a deficient number, since it is larger than the sum of its proper divisors (17383876).

21043436 is a wasteful number, since it uses less digits than its factorization.

21043436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228760 (or 228758 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 21043436 is about 4587.3125029804. The cubic root of 21043436 is about 276.0825035155.

Adding to 21043436 its reverse (63434012), we get a palindrome (84477448).

The spelling of 21043436 in words is "twenty-one million, forty-three thousand, four hundred thirty-six".