21130243 has 6 divisors (see below), whose sum is σ = 21652532. Its totient is φ = 20609400.

The previous prime is 21130231. The next prime is 21130247. The reversal of 21130243 is 34203112.

It is a happy number.

It is not a de Polignac number, because 21130243 - 2¹⁷ = 20999171 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21130247) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 29793 + ... + 30493.

Almost surely, 2^21130243 is an apocalyptic number.

21130243 is a deficient number, since it is larger than the sum of its proper divisors (522289).

21130243 is an frugal number, since it uses more digits than its factorization.

21130243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1445 (or 744 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 21130243 is about 4596.7644055357. The cubic root of 21130243 is about 276.4616085092.

Adding to 21130243 its reverse (34203112), we get a palindrome (55333355).

The spelling of 21130243 in words is "twenty-one million, one hundred thirty thousand, two hundred forty-three".