1666749 has 16 divisors (see below), whose sum is σ = 2562560. Its totient is φ = 943920.

The previous prime is 1666733. The next prime is 1666757. The reversal of 1666749 is 9476661.

It is not a de Polignac number, because 1666749 - 2⁴ = 1666733 is a prime.

1666749 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666729) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2634 + ... + 3204.

It is an arithmetic number, because the mean of its divisors is an integer number (160160).

2^1666749 is an apocalyptic number.

It is an amenable number.

1666749 is a deficient number, since it is larger than the sum of its proper divisors (895811).

1666749 is a wasteful number, since it uses less digits than its factorization.

1666749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 720.

The product of its digits is 54432, while the sum is 39.

The square root of 1666749 is about 1291.0263359049. The cubic root of 1666749 is about 118.5650624567.

It can be divided in two parts, 1666 and 749, that added together give a triangular number (2415 = T₆₉).

The spelling of 1666749 in words is "one million, six hundred sixty-six thousand, seven hundred forty-nine".