21103253 has 2 divisors, whose sum is σ = 21103254. Its totient is φ = 21103252.

The previous prime is 21103249. The next prime is 21103267. The reversal of 21103253 is 35230112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16337764 + 4765489 = 4042^2 + 2183^2 .

It is a cyclic number.

It is not a de Polignac number, because 21103253 - 2² = 21103249 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21103553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551626 + 10551627.

It is an arithmetic number, because the mean of its divisors is an integer number (10551627).

Almost surely, 2^21103253 is an apocalyptic number.

It is an amenable number.

21103253 is a deficient number, since it is larger than the sum of its proper divisors (1).

21103253 is an equidigital number, since it uses as much as digits as its factorization.

21103253 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 180, while the sum is 17.

The square root of 21103253 is about 4593.8277068258. The cubic root of 21103253 is about 276.3438487332.

Adding to 21103253 its reverse (35230112), we get a palindrome (56333365).

The spelling of 21103253 in words is "twenty-one million, one hundred three thousand, two hundred fifty-three".