1664986 has 4 divisors (see below), whose sum is σ = 2497482. Its totient is φ = 832492.

The previous prime is 1664959. The next prime is 1664987. The reversal of 1664986 is 6894661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 6894661 = 131 ⋅52631.

It can be written as a sum of positive squares in only one way, i.e., 1640961 + 24025 = 1281^2 + 155^2 .

It is not an unprimeable number, because it can be changed into a prime (1664987) 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, 416245 + ... + 416248.

2^1664986 is an apocalyptic number.

1664986 is a deficient number, since it is larger than the sum of its proper divisors (832496).

1664986 is an equidigital number, since it uses as much as digits as its factorization.

1664986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 832495.

The product of its digits is 62208, while the sum is 40.

The square root of 1664986 is about 1290.3433651552. The cubic root of 1664986 is about 118.5232437328.

The spelling of 1664986 in words is "one million, six hundred sixty-four thousand, nine hundred eighty-six".