1581666 has 8 divisors (see below), whose sum is σ = 3163344. Its totient is φ = 527220.

The previous prime is 1581653. The next prime is 1581673. The reversal of 1581666 is 6661851.

It is a sphenic number, since it is the product of 3 distinct primes.

1581666 is an admirable number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 131800 + ... + 131811.

It is an arithmetic number, because the mean of its divisors is an integer number (395418).

2^1581666 is an apocalyptic number.

1581666 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1581666 is a wasteful number, since it uses less digits than its factorization.

1581666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263616.

The product of its digits is 8640, while the sum is 33.

The square root of 1581666 is about 1257.6430336149. The cubic root of 1581666 is about 116.5122510402.

The spelling of 1581666 in words is "one million, five hundred eighty-one thousand, six hundred sixty-six".