1665611604 has 72 divisors (see below), whose sum is σ = 4286650368. Its totient is φ = 545227200.

The previous prime is 1665611599. The next prime is 1665611609. The reversal of 1665611604 is 4061165661.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1665611599) and next prime (1665611609).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665611609) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 459969 + ... + 463575.

Almost surely, 2^1665611604 is an apocalyptic number.

It is an amenable number.

1665611604 is an abundant number, since it is smaller than the sum of its proper divisors (2621038764).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1665611604 is a wasteful number, since it uses less digits than its factorization.

1665611604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3845 (or 3840 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The square root of 1665611604 is about 40811.9051748384. The cubic root of 1665611604 is about 1185.3808656640.

The spelling of 1665611604 in words is "one billion, six hundred sixty-five million, six hundred eleven thousand, six hundred four".