1664557 has 2 divisors, whose sum is σ = 1664558. Its totient is φ = 1664556.

The previous prime is 1664549. The next prime is 1664561. The reversal of 1664557 is 7554661.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1297321 + 367236 = 1139^2 + 606^2 .

It is a cyclic number.

It is not a de Polignac number, because 1664557 - 2³ = 1664549 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1664857) 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, 832278 + 832279.

It is an arithmetic number, because the mean of its divisors is an integer number (832279).

2^1664557 is an apocalyptic number.

It is an amenable number.

1664557 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664557 is an equidigital number, since it uses as much as digits as its factorization.

1664557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25200, while the sum is 34.

The square root of 1664557 is about 1290.1771196235. The cubic root of 1664557 is about 118.5130632990.

The spelling of 1664557 in words is "one million, six hundred sixty-four thousand, five hundred fifty-seven".