221601655081 has 2 divisors, whose sum is σ = 221601655082. Its totient is φ = 221601655080.

The previous prime is 221601655043. The next prime is 221601655141. The reversal of 221601655081 is 180556106122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 162744469056 + 58857186025 = 403416^2 + 242605^2 .

It is a cyclic number.

It is not a de Polignac number, because 221601655081 - 2¹¹ = 221601653033 is a prime.

It is a super-2 number, since 2×221601655081² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 221601655081.

It is not a weakly prime, because it can be changed into another prime (221601655181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110800827540 + 110800827541.

It is an arithmetic number, because the mean of its divisors is an integer number (110800827541).

Almost surely, 2^221601655081 is an apocalyptic number.

It is an amenable number.

221601655081 is a deficient number, since it is larger than the sum of its proper divisors (1).

221601655081 is an equidigital number, since it uses as much as digits as its factorization.

221601655081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 28800, while the sum is 37.

The spelling of 221601655081 in words is "two hundred twenty-one billion, six hundred one million, six hundred fifty-five thousand, eighty-one".