1664506 has 4 divisors (see below), whose sum is σ = 2496762. Its totient is φ = 832252.

The previous prime is 1664501. The next prime is 1664543. The reversal of 1664506 is 6054661.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 1010025 + 654481 = 1005^2 + 809^2 .

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (1664501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 416125 + ... + 416128.

2^1664506 is an apocalyptic number.

1664506 is a deficient number, since it is larger than the sum of its proper divisors (832256).

1664506 is an equidigital number, since it uses as much as digits as its factorization.

1664506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 832255.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 1664506 is about 1290.1573547440. The cubic root of 1664506 is about 118.5118529213.

The spelling of 1664506 in words is "one million, six hundred sixty-four thousand, five hundred six".