21217016620841 has 2 divisors, whose sum is σ = 21217016620842. Its totient is φ = 21217016620840.

The previous prime is 21217016620727. The next prime is 21217016620853. The reversal of 21217016620841 is 14802661071212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11558776032400 + 9658240588441 = 3399820^2 + 3107771^2 .

It is a cyclic number.

It is not a de Polignac number, because 21217016620841 - 2¹⁸ = 21217016358697 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21217016620861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10608508310420 + 10608508310421.

It is an arithmetic number, because the mean of its divisors is an integer number (10608508310421).

Almost surely, 2^{21217016620841} is an apocalyptic number.

It is an amenable number.

21217016620841 is a deficient number, since it is larger than the sum of its proper divisors (1).

21217016620841 is an equidigital number, since it uses as much as digits as its factorization.

21217016620841 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64512, while the sum is 41.

The spelling of 21217016620841 in words is "twenty-one trillion, two hundred seventeen billion, sixteen million, six hundred twenty thousand, eight hundred forty-one".