1666402 has 4 divisors (see below), whose sum is σ = 2499606. Its totient is φ = 833200.

The previous prime is 1666397. The next prime is 1666403. The reversal of 1666402 is 2046661.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 2046661 = 19 ⋅107719.

It can be written as a sum of positive squares in only one way, i.e., 1490841 + 175561 = 1221^2 + 419^2 .

It is not an unprimeable number, because it can be changed into a prime (1666403) 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, 416599 + ... + 416602.

2^1666402 is an apocalyptic number.

1666402 is a deficient number, since it is larger than the sum of its proper divisors (833204).

1666402 is an equidigital number, since it uses as much as digits as its factorization.

1666402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 833203.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 1666402 is about 1290.8919397068. The cubic root of 1666402 is about 118.5568338768.

The spelling of 1666402 in words is "one million, six hundred sixty-six thousand, four hundred two".