21191227 has 4 divisors (see below), whose sum is σ = 21333600. Its totient is φ = 21048856.

The previous prime is 21191201. The next prime is 21191239. The reversal of 21191227 is 72219112.

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 21191227 - 2¹⁹ = 20666939 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21141227) 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, 70963 + ... + 71260.

It is an arithmetic number, because the mean of its divisors is an integer number (5333400).

Almost surely, 2^21191227 is an apocalyptic number.

21191227 is a deficient number, since it is larger than the sum of its proper divisors (142373).

21191227 is a wasteful number, since it uses less digits than its factorization.

21191227 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 142372.

The product of its digits is 504, while the sum is 25.

The square root of 21191227 is about 4603.3929877863. The cubic root of 21191227 is about 276.7273183587.

The spelling of 21191227 in words is "twenty-one million, one hundred ninety-one thousand, two hundred twenty-seven".