21144205 has 12 divisors (see below), whose sum is σ = 26085780. Its totient is φ = 16452864.

The previous prime is 21144203. The next prime is 21144223. The reversal of 21144205 is 50244112.

It can be written as a sum of positive squares in 6 ways, for example, as 7387524 + 13756681 = 2718^2 + 3709^2 .

It is not a de Polignac number, because 21144205 - 2¹ = 21144203 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21144203) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5301 + ... + 8389.

It is an arithmetic number, because the mean of its divisors is an integer number (2173815).

Almost surely, 2^21144205 is an apocalyptic number.

It is an amenable number.

21144205 is a deficient number, since it is larger than the sum of its proper divisors (4941575).

21144205 is an equidigital number, since it uses as much as digits as its factorization.

21144205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3168 (or 3131 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 19.

The square root of 21144205 is about 4598.2828316666. The cubic root of 21144205 is about 276.5224866090.

Adding to 21144205 its reverse (50244112), we get a palindrome (71388317).

The spelling of 21144205 in words is "twenty-one million, one hundred forty-four thousand, two hundred five".