2118661 has 2 divisors, whose sum is σ = 2118662. Its totient is φ = 2118660.

The previous prime is 2118643. The next prime is 2118667. The reversal of 2118661 is 1668112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1454436 + 664225 = 1206^2 + 815^2 .

It is a cyclic number.

It is not a de Polignac number, because 2118661 - 2⁵ = 2118629 is a prime.

2118661 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2118667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1059330 + 1059331.

It is an arithmetic number, because the mean of its divisors is an integer number (1059331).

2^2118661 is an apocalyptic number.

It is an amenable number.

2118661 is a deficient number, since it is larger than the sum of its proper divisors (1).

2118661 is an equidigital number, since it uses as much as digits as its factorization.

2118661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 576, while the sum is 25.

The square root of 2118661 is about 1455.5620907402. The cubic root of 2118661 is about 128.4361141351.

The spelling of 2118661 in words is "two million, one hundred eighteen thousand, six hundred sixty-one".