21001535144441 has 2 divisors, whose sum is σ = 21001535144442. Its totient is φ = 21001535144440.

The previous prime is 21001535144423. The next prime is 21001535144467. The reversal of 21001535144441 is 14444153510012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19822619107600 + 1178916036841 = 4452260^2 + 1085779^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001535144441 - 2³⁸ = 20726657237497 is a prime.

It is not a weakly prime, because it can be changed into another prime (21001535144741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500767572220 + 10500767572221.

It is an arithmetic number, because the mean of its divisors is an integer number (10500767572221).

Almost surely, 2^{21001535144441} is an apocalyptic number.

It is an amenable number.

21001535144441 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001535144441 is an equidigital number, since it uses as much as digits as its factorization.

21001535144441 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 38400, while the sum is 35.

Adding to 21001535144441 its reverse (14444153510012), we get a palindrome (35445688654453).

The spelling of 21001535144441 in words is "twenty-one trillion, one billion, five hundred thirty-five million, one hundred forty-four thousand, four hundred forty-one".