2100120661 has 2 divisors, whose sum is σ = 2100120662. Its totient is φ = 2100120660.

The previous prime is 2100120647. The next prime is 2100120679. The reversal of 2100120661 is 1660210012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1498154436 + 601966225 = 38706^2 + 24535^2 .

It is a cyclic number.

It is not a de Polignac number, because 2100120661 - 2⁹ = 2100120149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2100120361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1050060330 + 1050060331.

It is an arithmetic number, because the mean of its divisors is an integer number (1050060331).

Almost surely, 2^2100120661 is an apocalyptic number.

It is an amenable number.

2100120661 is a deficient number, since it is larger than the sum of its proper divisors (1).

2100120661 is an equidigital number, since it uses as much as digits as its factorization.

2100120661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 2100120661 is about 45827.0734500906. The cubic root of 2100120661 is about 1280.6036908610.

Adding to 2100120661 its reverse (1660210012), we get a palindrome (3760330673).

The spelling of 2100120661 in words is "two billion, one hundred million, one hundred twenty thousand, six hundred sixty-one".