21001000253 has 2 divisors, whose sum is σ = 21001000254. Its totient is φ = 21001000252.

The previous prime is 21001000213. The next prime is 21001000259. The reversal of 21001000253 is 35200010012.

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., 14936017369 + 6064982884 = 122213^2 + 77878^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001000253 - 2¹⁴ = 21000983869 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21001000259) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500500126 + 10500500127.

It is an arithmetic number, because the mean of its divisors is an integer number (10500500127).

Almost surely, 2^21001000253 is an apocalyptic number.

It is an amenable number.

21001000253 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001000253 is an equidigital number, since it uses as much as digits as its factorization.

21001000253 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 60, while the sum is 14.

Adding to 21001000253 its reverse (35200010012), we get a palindrome (56201010265).

The spelling of 21001000253 in words is "twenty-one billion, one million, two hundred fifty-three", and thus it is an aban number.