21211147 has 4 divisors (see below), whose sum is σ = 21662496. Its totient is φ = 20759800.

The previous prime is 21211139. The next prime is 21211181. The reversal of 21211147 is 74111212.

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 21211147 - 2³ = 21211139 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21211247) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 225604 + ... + 225697.

It is an arithmetic number, because the mean of its divisors is an integer number (5415624).

Almost surely, 2^21211147 is an apocalyptic number.

21211147 is a deficient number, since it is larger than the sum of its proper divisors (451349).

21211147 is an equidigital number, since it uses as much as digits as its factorization.

21211147 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 451348.

The product of its digits is 112, while the sum is 19.

The square root of 21211147 is about 4605.5561010588. The cubic root of 21211147 is about 276.8140001703.

Adding to 21211147 its reverse (74111212), we get a palindrome (95322359).

The spelling of 21211147 in words is "twenty-one million, two hundred eleven thousand, one hundred forty-seven".