1667641 has 2 divisors, whose sum is σ = 1667642. Its totient is φ = 1667640.

The previous prime is 1667639. The next prime is 1667647. The reversal of 1667641 is 1467661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1638400 + 29241 = 1280^2 + 171^2 .

It is a cyclic number.

It is not a de Polignac number, because 1667641 - 2¹ = 1667639 is a prime.

Together with 1667639, it forms a pair of twin primes.

1667641 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (1667647) 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, 833820 + 833821.

It is an arithmetic number, because the mean of its divisors is an integer number (833821).

2^1667641 is an apocalyptic number.

It is an amenable number.

1667641 is a deficient number, since it is larger than the sum of its proper divisors (1).

1667641 is an equidigital number, since it uses as much as digits as its factorization.

1667641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6048, while the sum is 31.

The square root of 1667641 is about 1291.3717512785. The cubic root of 1667641 is about 118.5862096470.

The spelling of 1667641 in words is "one million, six hundred sixty-seven thousand, six hundred forty-one".