21225436 has 6 divisors (see below), whose sum is σ = 37144520. Its totient is φ = 10612716.

The previous prime is 21225431. The next prime is 21225437. The reversal of 21225436 is 63452212.

It is a self number, because there is not a number n which added to its sum of digits gives 21225436.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21225431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2653176 + ... + 2653183.

Almost surely, 2^21225436 is an apocalyptic number.

It is an amenable number.

21225436 is a deficient number, since it is larger than the sum of its proper divisors (15919084).

21225436 is a wasteful number, since it uses less digits than its factorization.

21225436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5306363 (or 5306361 counting only the distinct ones).

The product of its digits is 2880, while the sum is 25.

The square root of 21225436 is about 4607.1071183553. The cubic root of 21225436 is about 276.8761452835.

Adding to 21225436 its reverse (63452212), we get a palindrome (84677648).

The spelling of 21225436 in words is "twenty-one million, two hundred twenty-five thousand, four hundred thirty-six".