1604554661 has 2 divisors, whose sum is σ = 1604554662. Its totient is φ = 1604554660.

The previous prime is 1604554649. The next prime is 1604554663. The reversal of 1604554661 is 1664554061.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 802588900 + 801965761 = 28330^2 + 28319^2 .

It is a cyclic number.

It is not a de Polignac number, because 1604554661 - 2⁶ = 1604554597 is a prime.

Together with 1604554663, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1604554663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 802277330 + 802277331.

It is an arithmetic number, because the mean of its divisors is an integer number (802277331).

Almost surely, 2^1604554661 is an apocalyptic number.

It is an amenable number.

1604554661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1604554661 is an equidigital number, since it uses as much as digits as its factorization.

1604554661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 86400, while the sum is 38.

The square root of 1604554661 is about 40056.8928026126. The cubic root of 1604554661 is about 1170.7158696437.

The spelling of 1604554661 in words is "one billion, six hundred four million, five hundred fifty-four thousand, six hundred sixty-one".