1665918180 has 36 divisors (see below), whose sum is σ = 5053285692. Its totient is φ = 444244800.

The previous prime is 1665918173. The next prime is 1665918187. The reversal of 1665918180 is 818195661.

1665918180 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (1665918173) and next prime (1665918187).

It can be written as a sum of positive squares in 2 ways, for example, as 634737636 + 1031180544 = 25194^2 + 32112^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (1665918187) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4627371 + ... + 4627730.

It is an arithmetic number, because the mean of its divisors is an integer number (140369047).

Almost surely, 2^1665918180 is an apocalyptic number.

1665918180 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1665918180 is an abundant number, since it is smaller than the sum of its proper divisors (3387367512).

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

1665918180 is a wasteful number, since it uses less digits than its factorization.

1665918180 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9255116 (or 9255111 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 45.

The square root of 1665918180 is about 40815.6609648796. The cubic root of 1665918180 is about 1185.4535891067.

The spelling of 1665918180 in words is "one billion, six hundred sixty-five million, nine hundred eighteen thousand, one hundred eighty".