21541636243 has 2 divisors, whose sum is σ = 21541636244. Its totient is φ = 21541636242.

The previous prime is 21541636199. The next prime is 21541636271. The reversal of 21541636243 is 34263614512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21541636243 - 2¹³ = 21541628051 is a prime.

It is a super-3 number, since 3×21541636243³ (a number of 32 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (21541636043) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10770818121 + 10770818122.

It is an arithmetic number, because the mean of its divisors is an integer number (10770818122).

Almost surely, 2^21541636243 is an apocalyptic number.

21541636243 is a deficient number, since it is larger than the sum of its proper divisors (1).

21541636243 is an equidigital number, since it uses as much as digits as its factorization.

21541636243 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 103680, while the sum is 37.

The spelling of 21541636243 in words is "twenty-one billion, five hundred forty-one million, six hundred thirty-six thousand, two hundred forty-three".