21143969065601 has 2 divisors, whose sum is σ = 21143969065602. Its totient is φ = 21143969065600.

The previous prime is 21143969065591. The next prime is 21143969065613. The reversal of 21143969065601 is 10656096934112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21087336489025 + 56632576576 = 4592095^2 + 237976^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21143969065601 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 (21143969065651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10571984532800 + 10571984532801.

It is an arithmetic number, because the mean of its divisors is an integer number (10571984532801).

Almost surely, 2^{21143969065601} is an apocalyptic number.

It is an amenable number.

21143969065601 is a deficient number, since it is larger than the sum of its proper divisors (1).

21143969065601 is an equidigital number, since it uses as much as digits as its factorization.

21143969065601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2099520, while the sum is 53.

The spelling of 21143969065601 in words is "twenty-one trillion, one hundred forty-three billion, nine hundred sixty-nine million, sixty-five thousand, six hundred one".