1604212661 has 4 divisors (see below), whose sum is σ = 1604294412. Its totient is φ = 1604130912.

The previous prime is 1604212651. The next prime is 1604212669. The reversal of 1604212661 is 1662124061.

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.

It can be written as a sum of positive squares in 2 ways, for example, as 936972100 + 667240561 = 30610^2 + 25831^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1604212661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1604212669) 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, 8201 + ... + 57233.

It is an arithmetic number, because the mean of its divisors is an integer number (401073603).

Almost surely, 2^1604212661 is an apocalyptic number.

It is an amenable number.

1604212661 is a deficient number, since it is larger than the sum of its proper divisors (81751).

1604212661 is an equidigital number, since it uses as much as digits as its factorization.

1604212661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81750.

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 1604212661 is about 40052.6236468973. The cubic root of 1604212661 is about 1170.6326870039.

The spelling of 1604212661 in words is "one billion, six hundred four million, two hundred twelve thousand, six hundred sixty-one".