21718528253 has 2 divisors, whose sum is σ = 21718528254. Its totient is φ = 21718528252.

The previous prime is 21718528231. The next prime is 21718528283. The reversal of 21718528253 is 35282581712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17077785124 + 4640743129 = 130682^2 + 68123^2 .

It is a cyclic number.

It is not a de Polignac number, because 21718528253 - 2⁸ = 21718527997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21718528283) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10859264126 + 10859264127.

It is an arithmetic number, because the mean of its divisors is an integer number (10859264127).

Almost surely, 2^21718528253 is an apocalyptic number.

It is an amenable number.

21718528253 is a deficient number, since it is larger than the sum of its proper divisors (1).

21718528253 is an equidigital number, since it uses as much as digits as its factorization.

21718528253 is an evil number, because the sum of its binary digits is even.

The product of its digits is 268800, while the sum is 44.

The spelling of 21718528253 in words is "twenty-one billion, seven hundred eighteen million, five hundred twenty-eight thousand, two hundred fifty-three".