21278834750917 has 2 divisors, whose sum is σ = 21278834750918. Its totient is φ = 21278834750916.

The previous prime is 21278834750863. The next prime is 21278834750941. The reversal of 21278834750917 is 71905743887212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19329792592356 + 1949042158561 = 4396566^2 + 1396081^2 .

It is a cyclic number.

It is not a de Polignac number, because 21278834750917 - 2¹¹ = 21278834748869 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21278834756917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10639417375458 + 10639417375459.

It is an arithmetic number, because the mean of its divisors is an integer number (10639417375459).

Almost surely, 2^{21278834750917} is an apocalyptic number.

It is an amenable number.

21278834750917 is a deficient number, since it is larger than the sum of its proper divisors (1).

21278834750917 is an equidigital number, since it uses as much as digits as its factorization.

21278834750917 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 47416320, while the sum is 64.

The spelling of 21278834750917 in words is "twenty-one trillion, two hundred seventy-eight billion, eight hundred thirty-four million, seven hundred fifty thousand, nine hundred seventeen".