21540041357 has 2 divisors, whose sum is σ = 21540041358. Its totient is φ = 21540041356.

The previous prime is 21540041339. The next prime is 21540041387. The reversal of 21540041357 is 75314004512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14064536836 + 7475504521 = 118594^2 + 86461^2 .

It is a cyclic number.

It is not a de Polignac number, because 21540041357 - 2²⁴ = 21523264141 is a prime.

It is a super-2 number, since 2×21540041357² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21540041387) 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, 10770020678 + 10770020679.

It is an arithmetic number, because the mean of its divisors is an integer number (10770020679).

Almost surely, 2^21540041357 is an apocalyptic number.

It is an amenable number.

21540041357 is a deficient number, since it is larger than the sum of its proper divisors (1).

21540041357 is an equidigital number, since it uses as much as digits as its factorization.

21540041357 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16800, while the sum is 32.

Adding to 21540041357 its reverse (75314004512), we get a palindrome (96854045869).

The spelling of 21540041357 in words is "twenty-one billion, five hundred forty million, forty-one thousand, three hundred fifty-seven".