21130245 has 12 divisors (see below), whose sum is σ = 36625836. Its totient is φ = 11269440.

The previous prime is 21130231. The next prime is 21130247. The reversal of 21130245 is 54203112.

It can be written as a sum of positive squares in 2 ways, for example, as 6796449 + 14333796 = 2607^2 + 3786^2 .

It is not a de Polignac number, because 21130245 - 2⁸ = 21129989 is a prime.

It is a congruent 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 11 ways as a sum of consecutive naturals, for example, 234736 + ... + 234825.

It is an arithmetic number, because the mean of its divisors is an integer number (3052153).

Almost surely, 2^21130245 is an apocalyptic number.

It is an amenable number.

21130245 is a deficient number, since it is larger than the sum of its proper divisors (15495591).

21130245 is a wasteful number, since it uses less digits than its factorization.

21130245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 469572 (or 469569 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21130245 is about 4596.7646230800. The cubic root of 21130245 is about 276.4616172317.

Adding to 21130245 its reverse (54203112), we get a palindrome (75333357).

The spelling of 21130245 in words is "twenty-one million, one hundred thirty thousand, two hundred forty-five".