1666537 has 4 divisors (see below), whose sum is σ = 1669120. Its totient is φ = 1663956.

The previous prime is 1666531. The next prime is 1666541. The reversal of 1666537 is 7356661.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 1666537 - 2⁷ = 1666409 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666531) 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 in 3 ways as a sum of consecutive naturals, for example, 628 + ... + 1930.

It is an arithmetic number, because the mean of its divisors is an integer number (417280).

2^1666537 is an apocalyptic number.

It is an amenable number.

1666537 is a deficient number, since it is larger than the sum of its proper divisors (2583).

1666537 is a wasteful number, since it uses less digits than its factorization.

1666537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2582.

The product of its digits is 22680, while the sum is 34.

The square root of 1666537 is about 1290.9442280749. The cubic root of 1666537 is about 118.5600353333.

It can be divided in two parts, 16665 and 37, that multiplied together give a triangular number (616605 = T₁₁₁₀).

The spelling of 1666537 in words is "one million, six hundred sixty-six thousand, five hundred thirty-seven".