1918661 has 2 divisors, whose sum is σ = 1918662. Its totient is φ = 1918660.

The previous prime is 1918649. The next prime is 1918667. The reversal of 1918661 is 1668191.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1288225 + 630436 = 1135^2 + 794^2 .

It is a cyclic number.

It is not a de Polignac number, because 1918661 - 2¹⁸ = 1656517 is a prime.

It is a Chen prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1918667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 959330 + 959331.

It is an arithmetic number, because the mean of its divisors is an integer number (959331).

2^1918661 is an apocalyptic number.

It is an amenable number.

1918661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1918661 is an equidigital number, since it uses as much as digits as its factorization.

1918661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2592, while the sum is 32.

The square root of 1918661 is about 1385.1573917790. The cubic root of 1918661 is about 124.2604005722.

The spelling of 1918661 in words is "one million, nine hundred eighteen thousand, six hundred sixty-one".