1604561 has 4 divisors (see below), whose sum is σ = 1833792. Its totient is φ = 1375332.

The previous prime is 1604557. The next prime is 1604567. The reversal of 1604561 is 1654061.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1654061 = 977 ⋅1693.

It is not a de Polignac number, because 1604561 - 2² = 1604557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1604567) 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, 114605 + ... + 114618.

It is an arithmetic number, because the mean of its divisors is an integer number (458448).

2^1604561 is an apocalyptic number.

It is an amenable number.

1604561 is a deficient number, since it is larger than the sum of its proper divisors (229231).

1604561 is an equidigital number, since it uses as much as digits as its factorization.

1604561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 229230.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 1604561 is about 1266.7126746030. The cubic root of 1604561 is about 117.0717411330.

The spelling of 1604561 in words is "one million, six hundred four thousand, five hundred sixty-one".