1604555551 has 4 divisors (see below), whose sum is σ = 1605361032. Its totient is φ = 1603750072.

The previous prime is 1604555531. The next prime is 1604555573. The reversal of 1604555551 is 1555554061.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1604555551 - 2⁷ = 1604555423 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1604555551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1604555501) 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 in 3 ways as a sum of consecutive naturals, for example, 399745 + ... + 403738.

It is an arithmetic number, because the mean of its divisors is an integer number (401340258).

Almost surely, 2^1604555551 is an apocalyptic number.

1604555551 is a deficient number, since it is larger than the sum of its proper divisors (805481).

1604555551 is an equidigital number, since it uses as much as digits as its factorization.

1604555551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 805480.

The product of its (nonzero) digits is 75000, while the sum is 37.

The square root of 1604555551 is about 40056.9039118103. The cubic root of 1604555551 is about 1170.7160860977.

The spelling of 1604555551 in words is "one billion, six hundred four million, five hundred fifty-five thousand, five hundred fifty-one".