21140221 has 4 divisors (see below), whose sum is σ = 21486844. Its totient is φ = 20793600.

The previous prime is 21140213. The next prime is 21140237. The reversal of 21140221 is 12204112.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 4575321 + 16564900 = 2139^2 + 4070^2 .

It is a cyclic number.

It is not a de Polignac number, because 21140221 - 2³ = 21140213 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21140201) 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, 173220 + ... + 173341.

It is an arithmetic number, because the mean of its divisors is an integer number (5371711).

Almost surely, 2^21140221 is an apocalyptic number.

It is an amenable number.

21140221 is a deficient number, since it is larger than the sum of its proper divisors (346623).

21140221 is an equidigital number, since it uses as much as digits as its factorization.

21140221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 346622.

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 21140221 is about 4597.8496060659. The cubic root of 21140221 is about 276.5051180237.

Adding to 21140221 its reverse (12204112), we get a palindrome (33344333).

The spelling of 21140221 in words is "twenty-one million, one hundred forty thousand, two hundred twenty-one".