21840616646081 has 2 divisors, whose sum is σ = 21840616646082. Its totient is φ = 21840616646080.

The previous prime is 21840616646039. The next prime is 21840616646153. The reversal of 21840616646081 is 18064661604812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20180085450625 + 1660531195456 = 4492225^2 + 1288616^2 .

It is a cyclic number.

It is not a de Polignac number, because 21840616646081 - 2²⁶ = 21840549537217 is a prime.

It is a super-2 number, since 2×21840616646081² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21840616646021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10920308323040 + 10920308323041.

It is an arithmetic number, because the mean of its divisors is an integer number (10920308323041).

Almost surely, 2^{21840616646081} is an apocalyptic number.

It is an amenable number.

21840616646081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21840616646081 is an equidigital number, since it uses as much as digits as its factorization.

21840616646081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2654208, while the sum is 53.

The spelling of 21840616646081 in words is "twenty-one trillion, eight hundred forty billion, six hundred sixteen million, six hundred forty-six thousand, eighty-one".