1366991 has 2 divisors, whose sum is σ = 1366992. Its totient is φ = 1366990.

The previous prime is 1366979. The next prime is 1366997. The reversal of 1366991 is 1996631.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1366991 - 2¹⁴ = 1350607 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1366997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 683495 + 683496.

It is an arithmetic number, because the mean of its divisors is an integer number (683496).

2^1366991 is an apocalyptic number.

1366991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1366991 is an equidigital number, since it uses as much as digits as its factorization.

1366991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8748, while the sum is 35.

The square root of 1366991 is about 1169.1839034130. The cubic root of 1366991 is about 110.9826826865.

The spelling of 1366991 in words is "one million, three hundred sixty-six thousand, nine hundred ninety-one".