21363253 has 2 divisors, whose sum is σ = 21363254. Its totient is φ = 21363252.

The previous prime is 21363193. The next prime is 21363257. The reversal of 21363253 is 35236312.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14799409 + 6563844 = 3847^2 + 2562^2 .

It is a cyclic number.

It is not a de Polignac number, because 21363253 - 2⁹ = 21362741 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21363257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10681626 + 10681627.

It is an arithmetic number, because the mean of its divisors is an integer number (10681627).

Almost surely, 2^21363253 is an apocalyptic number.

It is an amenable number.

21363253 is a deficient number, since it is larger than the sum of its proper divisors (1).

21363253 is an equidigital number, since it uses as much as digits as its factorization.

21363253 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3240, while the sum is 25.

The square root of 21363253 is about 4622.0399176121. The cubic root of 21363253 is about 277.4741062872.

Adding to 21363253 its reverse (35236312), we get a palindrome (56599565).

The spelling of 21363253 in words is "twenty-one million, three hundred sixty-three thousand, two hundred fifty-three".