21454540343521 has 4 divisors (see below), whose sum is σ = 22716572128452. Its totient is φ = 20192508558592.

The previous prime is 21454540343497. The next prime is 21454540343543. The reversal of 21454540343521 is 12534304545412.

It is a happy number.

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 19042619526225 + 2411920817296 = 4363785^2 + 1553036^2 .

It is a cyclic number.

It is not a de Polignac number, because 21454540343521 - 2⁷ = 21454540343393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21454540343581) 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 in 3 ways as a sum of consecutive naturals, for example, 631015892440 + ... + 631015892473.

It is an arithmetic number, because the mean of its divisors is an integer number (5679143032113).

Almost surely, 2^{21454540343521} is an apocalyptic number.

It is an amenable number.

21454540343521 is a deficient number, since it is larger than the sum of its proper divisors (1262031784931).

21454540343521 is a wasteful number, since it uses less digits than its factorization.

21454540343521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1262031784930.

The product of its (nonzero) digits is 1152000, while the sum is 43.

Adding to 21454540343521 its reverse (12534304545412), we get a palindrome (33988844888933).

The spelling of 21454540343521 in words is "twenty-one trillion, four hundred fifty-four billion, five hundred forty million, three hundred forty-three thousand, five hundred twenty-one".