21237804492517 has 2 divisors, whose sum is σ = 21237804492518. Its totient is φ = 21237804492516.

The previous prime is 21237804492493. The next prime is 21237804492533. The reversal of 21237804492517 is 71529440873212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15543787238721 + 5694017253796 = 3942561^2 + 2386214^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21237804492517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21237804492557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10618902246258 + 10618902246259.

It is an arithmetic number, because the mean of its divisors is an integer number (10618902246259).

Almost surely, 2^{21237804492517} is an apocalyptic number.

It is an amenable number.

21237804492517 is a deficient number, since it is larger than the sum of its proper divisors (1).

21237804492517 is an equidigital number, since it uses as much as digits as its factorization.

21237804492517 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6773760, while the sum is 55.

The spelling of 21237804492517 in words is "twenty-one trillion, two hundred thirty-seven billion, eight hundred four million, four hundred ninety-two thousand, five hundred seventeen".