1661406 has 8 divisors (see below), whose sum is σ = 3322824. Its totient is φ = 553800.

The previous prime is 1661353. The next prime is 1661431. The reversal of 1661406 is 6041661.

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

1661406 is an admirable number.

It is a congruent number.

It is an unprimeable number.

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, 138445 + ... + 138456.

It is an arithmetic number, because the mean of its divisors is an integer number (415353).

2^1661406 is an apocalyptic number.

1661406 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.

1661406 is a wasteful number, since it uses less digits than its factorization.

1661406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 276906.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 1661406 is about 1288.9553910047. The cubic root of 1661406 is about 118.4382344712.

The spelling of 1661406 in words is "one million, six hundred sixty-one thousand, four hundred six".