1906561 has 4 divisors (see below), whose sum is σ = 1909332. Its totient is φ = 1903792.

The previous prime is 1906559. The next prime is 1906579. The reversal of 1906561 is 1656091.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1656091 = 53 ⋅31247.

It can be written as a sum of positive squares in 2 ways, for example, as 1476225 + 430336 = 1215^2 + 656^2 .

It is a cyclic number.

It is not a de Polignac number, because 1906561 - 2¹ = 1906559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1906511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 531 + ... + 2023.

It is an arithmetic number, because the mean of its divisors is an integer number (477333).

2^1906561 is an apocalyptic number.

It is an amenable number.

1906561 is a deficient number, since it is larger than the sum of its proper divisors (2771).

1906561 is a wasteful number, since it uses less digits than its factorization.

1906561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2770.

The product of its (nonzero) digits is 1620, while the sum is 28.

The square root of 1906561 is about 1380.7827490232. The cubic root of 1906561 is about 123.9986342201.

The spelling of 1906561 in words is "one million, nine hundred six thousand, five hundred sixty-one".