16643413561 has 2 divisors, whose sum is σ = 16643413562. Its totient is φ = 16643413560.

The previous prime is 16643413543. The next prime is 16643413609. The reversal of 16643413561 is 16531434661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8860645161 + 7782768400 = 94131^2 + 88220^2 .

It is a cyclic number.

It is not a de Polignac number, because 16643413561 - 2¹³ = 16643405369 is a prime.

It is not a weakly prime, because it can be changed into another prime (16643413511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8321706780 + 8321706781.

It is an arithmetic number, because the mean of its divisors is an integer number (8321706781).

Almost surely, 2^16643413561 is an apocalyptic number.

It is an amenable number.

16643413561 is a deficient number, since it is larger than the sum of its proper divisors (1).

16643413561 is an equidigital number, since it uses as much as digits as its factorization.

16643413561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 155520, while the sum is 40.

The spelling of 16643413561 in words is "sixteen billion, six hundred forty-three million, four hundred thirteen thousand, five hundred sixty-one".