21315236253 has 4 divisors (see below), whose sum is σ = 28420315008. Its totient is φ = 14210157500.

The previous prime is 21315236233. The next prime is 21315236303. The reversal of 21315236253 is 35263251312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21315236253 - 2¹² = 21315232157 is a prime.

It is a super-3 number, since 3×21315236253³ (a number of 32 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21315236233) 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, 3552539373 + ... + 3552539378.

It is an arithmetic number, because the mean of its divisors is an integer number (7105078752).

Almost surely, 2^21315236253 is an apocalyptic number.

It is an amenable number.

21315236253 is a deficient number, since it is larger than the sum of its proper divisors (7105078755).

21315236253 is an equidigital number, since it uses as much as digits as its factorization.

21315236253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7105078754.

The product of its digits is 32400, while the sum is 33.

Adding to 21315236253 its reverse (35263251312), we get a palindrome (56578487565).

The spelling of 21315236253 in words is "twenty-one billion, three hundred fifteen million, two hundred thirty-six thousand, two hundred fifty-three".