21507536443397 has 2 divisors, whose sum is σ = 21507536443398. Its totient is φ = 21507536443396.

The previous prime is 21507536443241. The next prime is 21507536443399. The reversal of 21507536443397 is 79334463570512.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16343148387556 + 5164388055841 = 4042666^2 + 2272529^2 .

It is a cyclic number.

It is not a de Polignac number, because 21507536443397 - 2¹⁰ = 21507536442373 is a prime.

Together with 21507536443399, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21507536443399) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753768221698 + 10753768221699.

It is an arithmetic number, because the mean of its divisors is an integer number (10753768221699).

Almost surely, 2^{21507536443397} is an apocalyptic number.

It is an amenable number.

21507536443397 is a deficient number, since it is larger than the sum of its proper divisors (1).

21507536443397 is an equidigital number, since it uses as much as digits as its factorization.

21507536443397 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 57153600, while the sum is 59.

The spelling of 21507536443397 in words is "twenty-one trillion, five hundred seven billion, five hundred thirty-six million, four hundred forty-three thousand, three hundred ninety-seven".