21143891017 has 2 divisors, whose sum is σ = 21143891018. Its totient is φ = 21143891016.

The previous prime is 21143890997. The next prime is 21143891023. The reversal of 21143891017 is 71019834112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16229740816 + 4914150201 = 127396^2 + 70101^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21143891017 is a prime.

It is not a weakly prime, because it can be changed into another prime (21143891077) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10571945508 + 10571945509.

It is an arithmetic number, because the mean of its divisors is an integer number (10571945509).

Almost surely, 2^21143891017 is an apocalyptic number.

It is an amenable number.

21143891017 is a deficient number, since it is larger than the sum of its proper divisors (1).

21143891017 is an equidigital number, since it uses as much as digits as its factorization.

21143891017 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12096, while the sum is 37.

The spelling of 21143891017 in words is "twenty-one billion, one hundred forty-three million, eight hundred ninety-one thousand, seventeen".