1665213918 has 32 divisors (see below), whose sum is σ = 3441426432. Its totient is φ = 536608800.

The previous prime is 1665213917. The next prime is 1665213919. The reversal of 1665213918 is 8193125661.

It is an interprime number because it is at equal distance from previous prime (1665213917) and next prime (1665213919).

It is a self number, because there is not a number n which added to its sum of digits gives 1665213918.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665213917) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 199203 + ... + 207393.

It is an arithmetic number, because the mean of its divisors is an integer number (107544576).

Almost surely, 2^1665213918 is an apocalyptic number.

1665213918 is an abundant number, since it is smaller than the sum of its proper divisors (1776212514).

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

1665213918 is a wasteful number, since it uses less digits than its factorization.

1665213918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9320.

The product of its digits is 77760, while the sum is 42.

The square root of 1665213918 is about 40807.0327027095. The cubic root of 1665213918 is about 1185.2865165579.

The spelling of 1665213918 in words is "one billion, six hundred sixty-five million, two hundred thirteen thousand, nine hundred eighteen".