21227747 has 4 divisors (see below), whose sum is σ = 22476456. Its totient is φ = 19979040.

The previous prime is 21227711. The next prime is 21227753. The reversal of 21227747 is 74772212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21227747 - 2¹² = 21223651 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21227707) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 624329 + ... + 624362.

It is an arithmetic number, because the mean of its divisors is an integer number (5619114).

Almost surely, 2^21227747 is an apocalyptic number.

21227747 is a deficient number, since it is larger than the sum of its proper divisors (1248709).

21227747 is a wasteful number, since it uses less digits than its factorization.

21227747 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1248708.

The product of its digits is 10976, while the sum is 32.

The square root of 21227747 is about 4607.3579196759. The cubic root of 21227747 is about 276.8861935663.

Adding to 21227747 its reverse (74772212), we get a palindrome (95999959).

The spelling of 21227747 in words is "twenty-one million, two hundred twenty-seven thousand, seven hundred forty-seven".