1665564400 has 30 divisors (see below), whose sum is σ = 4001519432. Its totient is φ = 666225600.

The previous prime is 1665564371. The next prime is 1665564401. The reversal of 1665564400 is 44655661.

It is a self number, because there is not a number n which added to its sum of digits gives 1665564400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665564401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2081556 + ... + 2082355.

Almost surely, 2^1665564400 is an apocalyptic number.

1665564400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1665564400 is an abundant number, since it is smaller than the sum of its proper divisors (2335955032).

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

1665564400 is a wasteful number, since it uses less digits than its factorization.

1665564400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4163929 (or 4163918 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 37.

The square root of 1665564400 is about 40811.3268590964. The cubic root of 1665564400 is about 1185.3696675258.

The spelling of 1665564400 in words is "one billion, six hundred sixty-five million, five hundred sixty-four thousand, four hundred".