1091609 has 2 divisors, whose sum is σ = 1091610. Its totient is φ = 1091608.

The previous prime is 1091591. The next prime is 1091617. The reversal of 1091609 is 9061901.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 697225 + 394384 = 835^2 + 628^2 .

It is a cyclic number.

It is not a de Polignac number, because 1091609 - 2¹⁶ = 1026073 is a prime.

It is a super-2 number, since 2×1091609² = 2383220417762, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1091639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 545804 + 545805.

It is an arithmetic number, because the mean of its divisors is an integer number (545805).

2^1091609 is an apocalyptic number.

It is an amenable number.

1091609 is a deficient number, since it is larger than the sum of its proper divisors (1).

1091609 is an equidigital number, since it uses as much as digits as its factorization.

1091609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 486, while the sum is 26.

The square root of 1091609 is about 1044.8009379781. The cubic root of 1091609 is about 102.9648606057.

It can be divided in two parts, 10 and 91609, that added together give a palindrome (91619).

The spelling of 1091609 in words is "one million, ninety-one thousand, six hundred nine".