1664549 has 2 divisors, whose sum is σ = 1664550. Its totient is φ = 1664548.

The previous prime is 1664543. The next prime is 1664557. The reversal of 1664549 is 9454661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1643524 + 21025 = 1282^2 + 145^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1664549 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1664543) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832274 + 832275.

It is an arithmetic number, because the mean of its divisors is an integer number (832275).

2^1664549 is an apocalyptic number.

It is an amenable number.

1664549 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664549 is an equidigital number, since it uses as much as digits as its factorization.

1664549 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 35.

The square root of 1664549 is about 1290.1740192703. The cubic root of 1664549 is about 118.5128734375.

The spelling of 1664549 in words is "one million, six hundred sixty-four thousand, five hundred forty-nine".