21310253 has 2 divisors, whose sum is σ = 21310254. Its totient is φ = 21310252.

The previous prime is 21310243. The next prime is 21310271. The reversal of 21310253 is 35201312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17322244 + 3988009 = 4162^2 + 1997^2 .

It is a cyclic number.

It is not a de Polignac number, because 21310253 - 2⁶ = 21310189 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a zygodrome in base 3.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21310243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655126 + 10655127.

It is an arithmetic number, because the mean of its divisors is an integer number (10655127).

Almost surely, 2^21310253 is an apocalyptic number.

It is an amenable number.

21310253 is a deficient number, since it is larger than the sum of its proper divisors (1).

21310253 is an equidigital number, since it uses as much as digits as its factorization.

21310253 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 21310253 is about 4616.3029579957. The cubic root of 21310253 is about 277.2444548404.

Adding to 21310253 its reverse (35201312), we get a palindrome (56511565).

The spelling of 21310253 in words is "twenty-one million, three hundred ten thousand, two hundred fifty-three".