1218691 has 2 divisors, whose sum is σ = 1218692. Its totient is φ = 1218690.

The previous prime is 1218683. The next prime is 1218709. The reversal of 1218691 is 1968121.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1218691 - 2³ = 1218683 is a prime.

It is not a weakly prime, because it can be changed into another prime (1218601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 609345 + 609346.

It is an arithmetic number, because the mean of its divisors is an integer number (609346).

2^1218691 is an apocalyptic number.

1218691 is a deficient number, since it is larger than the sum of its proper divisors (1).

1218691 is an equidigital number, since it uses as much as digits as its factorization.

1218691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 864, while the sum is 28.

The square root of 1218691 is about 1103.9433862296. The cubic root of 1218691 is about 106.8147433438.

The spelling of 1218691 in words is "one million, two hundred eighteen thousand, six hundred ninety-one".