1666551 has 8 divisors (see below), whose sum is σ = 2273920. Its totient is φ = 1085112.

The previous prime is 1666541. The next prime is 1666559. The reversal of 1666551 is 1556661.

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

It is not a de Polignac number, because 1666551 - 2⁵ = 1666519 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 (1666559) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6331 + ... + 6588.

It is an arithmetic number, because the mean of its divisors is an integer number (284240).

2^1666551 is an apocalyptic number.

1666551 is a deficient number, since it is larger than the sum of its proper divisors (607369).

1666551 is a wasteful number, since it uses less digits than its factorization.

1666551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12965.

The product of its digits is 5400, while the sum is 30.

The square root of 1666551 is about 1290.9496504512. The cubic root of 1666551 is about 118.5603673263.

The spelling of 1666551 in words is "one million, six hundred sixty-six thousand, five hundred fifty-one".