2161221061 has 2 divisors, whose sum is σ = 2161221062. Its totient is φ = 2161221060.

The previous prime is 2161220977. The next prime is 2161221071. The reversal of 2161221061 is 1601221612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2096724100 + 64496961 = 45790^2 + 8031^2 .

It is a cyclic number.

It is not a de Polignac number, because 2161221061 - 2¹¹ = 2161219013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2161221071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1080610530 + 1080610531.

It is an arithmetic number, because the mean of its divisors is an integer number (1080610531).

Almost surely, 2^2161221061 is an apocalyptic number.

It is an amenable number.

2161221061 is a deficient number, since it is larger than the sum of its proper divisors (1).

2161221061 is an equidigital number, since it uses as much as digits as its factorization.

2161221061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 2161221061 is about 46488.9348232458. The cubic root of 2161221061 is about 1292.9043511133.

Adding to 2161221061 its reverse (1601221612), we get a palindrome (3762442673).

The spelling of 2161221061 in words is "two billion, one hundred sixty-one million, two hundred twenty-one thousand, sixty-one".