1906661 has 4 divisors (see below), whose sum is σ = 1909824. Its totient is φ = 1903500.

The previous prime is 1906643. The next prime is 1906673. The reversal of 1906661 is 1666091.

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.

It is a cyclic number.

It is not a de Polignac number, because 1906661 - 2¹⁴ = 1890277 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1906621) 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, 365 + ... + 1986.

It is an arithmetic number, because the mean of its divisors is an integer number (477456).

2^1906661 is an apocalyptic number.

It is an amenable number.

1906661 is a deficient number, since it is larger than the sum of its proper divisors (3163).

1906661 is an equidigital number, since it uses as much as digits as its factorization.

1906661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3162.

The product of its (nonzero) digits is 1944, while the sum is 29.

The square root of 1906661 is about 1380.8189598930. The cubic root of 1906661 is about 124.0008021107. Note that the first 3 decimals are identical.

The spelling of 1906661 in words is "one million, nine hundred six thousand, six hundred sixty-one".