1604 has 6 divisors (see below), whose sum is σ = 2814. Its totient is φ = 800.

The previous prime is 1601. The next prime is 1607. The reversal of 1604 is 4061.

1604 is nontrivially palindromic in base 3 and base 14.

1604 is an esthetic number in base 4, because in such base its adjacent digits differ by 1.

It is an interprime number because it is at equal distance from previous prime (1601) and next prime (1607).

It can be written as a sum of positive squares in only one way, i.e., 1600 + 4 = 40^2 + 2^2 .

It is an Ulam number.

1604 is an undulating number in base 14.

It is a plaindrome in base 11.

It is a nialpdrome in base 13 and base 16.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 1604.

It is not an unprimeable number, because it can be changed into a prime (1601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 197 + ... + 204.

It is an arithmetic number, because the mean of its divisors is an integer number (469).

It is an amenable number.

1604 is a deficient number, since it is larger than the sum of its proper divisors (1210).

1604 is a wasteful number, since it uses less digits than its factorization.

1604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 405 (or 403 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 1604 is about 40.0499687890. The cubic root of 1604 is about 11.7058095676.

Adding to 1604 its reverse (4061), we get a palindrome (5665).

The spelling of 1604 in words is "one thousand, six hundred four".