21043263253 has 4 divisors (see below), whose sum is σ = 21046960108. Its totient is φ = 21039566400.

The previous prime is 21043263239. The next prime is 21043263257. The reversal of 21043263253 is 35236234012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14827202289 + 6216060964 = 121767^2 + 78842^2 .

It is a cyclic number.

It is not a de Polignac number, because 21043263253 - 2³³ = 12453328661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21043263257) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1839876 + ... + 1851277.

It is an arithmetic number, because the mean of its divisors is an integer number (5261740027).

Almost surely, 2^21043263253 is an apocalyptic number.

It is an amenable number.

21043263253 is a deficient number, since it is larger than the sum of its proper divisors (3696855).

21043263253 is an equidigital number, since it uses as much as digits as its factorization.

21043263253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3696854.

The product of its (nonzero) digits is 25920, while the sum is 31.

Adding to 21043263253 its reverse (35236234012), we get a palindrome (56279497265).

The spelling of 21043263253 in words is "twenty-one billion, forty-three million, two hundred sixty-three thousand, two hundred fifty-three".